I haven't played V in aggges, so I will defer to your statement; but I still don't think VI's menu screens are that much more blue than V's are black. Those are well n truly the dominant colours in both schemes.
You don't need to take my word for it. Just Google "Civ V main menus" or "Civ V Gods and Kings menu" or "Civ V Brave New World Menu" and compare them with the Civ VI menus. The Civ VI menus throughout all expansions notably use blue and white not just for the menus themselves (New Game, Load Game, etc), but for the backdrop images and animations. Civ V used a range of colors from gold to blue, brown, and so on--still a unified color scheme, but nowhere near as plasticky as Civ VI's.
I have agreed there are a few clangers in VI. The PT Barnum one is especially egregious, and you can hear it in Bean's voice as he is bored half to death reading one of the most obvious statements ever made
But it's not the end of the world. Not to mention much of that will be subjective. Some people think the Monty Python ones shouldn't be in there; but I love them
I will point out too that there are more clangers in Civ VI as you put it, IMO, than in prior Civ entries. I think that's disappointing. While I was excited for Sean Bean to be the narrator, I think Sean Bean didn't deliver on the Monty Python ones as well, and frankly quotes with more gravitas and less cynicism would have suited his peaceful voice (I liked his work in Elder Scrolls IV: Oblivion more, but then, he had somewhat better material to work with there IMO.)
Yes, agreed on the Civilopedia; but again, that isn't the end of the world either. You can find most the information you're looking for at sites like this and Civilization Wiki without even being in the game at all.
No critique of a game needs to say a flaw is "the end of the world" to be a valid criticism. And it would be handier to have the Civilopedia accessible from the main menu. After all, for some new Civ fans, they may very well be interested on who is who among the interesting leaders in Civ VI, and/or want to read stuff on the mechanics of the game from the main menu right before launching into a new game.
I suspect re the music they remember the backlash from IV when Warlords replaced the magnificent Baba yetu with some much more plain muted tune. By the time BTS was released they allowed people (rightly) to select between those two and BTS's choral type music. I'm going to guess that 90% of players went back to Baba Yetu, and so with this they have decided to just have Sogno di Volare, as that would be easily almost as popular. I'd rather (as I said) be able to revert back to the vanilla screen behind the menu's. Still, we only spend a small amount of time in the menu's...so 
Sure, we don't spend too much time on the menus (though I will point out ahead of each gameplay session we have to encounter them). But they are a significant part of a gameplay experience given that first impressions last, and also given that many Steam owners of the game likely haven't even played more than a few minutes of Civ (somewhere on these forums there was a thread about the percentage of Steam users who ever won a Civ game--it was lower than even I expected).
Re: the Civ IV Warlords music, I disagree that it was a "much more plain muted theme" and don't recall any backlash. I quite liked the Al Nadda musical theme of Warlords, and I think it was a rich, catchy banger of a tune, even if not as magnificent as Baba Yetu. But at least we have the choice in Civ IV--as you mentioned, you can switch menu themes and menu music in Civ IV, so that's a non-issue. In Civ VI you have the "choice" of one main menu theme and that's it. Even if more people would have preferred Sogno di Volare as the main menu theme, how can Firaxis (or anyone) know, without giving us other options to compare?
For those interested, the Civ IV Al Nadda Warlords theme is here (it's a love song that sounds like a war song):
Frankly, the lack of musical menu options in Civ VI throughout expansions is just another example of the kind of obvious cost-cutting that Civ VI introduced to the Civ series (another example of this is the replacement of animated leader backgrounds with smudged paintings bearing dolorously muted colors, and the use of cutscenes for most leader interactions, rather than having real-time voiced over leader interaction). While it's not necessarily something that would kill the game, it undercuts excitement at an expansion when one sees less new material in the music and art department, even if visible just on the main menu.
Heck, Civ V even had different music for each scenario loading screen (for example, Messe Notre Dame for the Medieval World scenario).
And? Gravita's isn't everything. Civ has, as
@Lord Lakely said, traditionally been quite flippant. Which I always like when the game got serious - there was always a silly undercurrent. Having other leaders rage at you all game long over doing the same stuff they're doing does get tiresome. Having a wink and nudge in there can make a world of difference.
I did like the smaller units from V that were more in scale with the cities etc. I think that was a good development. I get that VI wanted to make it easy for people to see how many charges units had; and possibly also felt that it was easier to see unit strength represented in fewer units. I don't think they're right on the latter; and would also like to see a return to more scale appropriate size units. Hell, at least it's not as bad as Humankind on that level where you have both small animals and large animals; and small people and large people! That...it's just plain weird!
I never said that gravitas is "everything". Critiquing the lack of gravitas in Civ VI need not be accompanied by evidence that 'gravitas is everything' to be valid. Moreover, I only bother with such criticisms because I love the Civ series and, like any rabid fan, I always want it to be the best it can be. Right now, Civ VI is a disappointment in the gravitas department for sure.
Civ has been traditionally flippant in select areas, and not in others (Civ IV for example had quotes with far more gravitas, a dangerously intelligent set of AIs that could fight wars properly, and complex diplomatic systems that make the World Congress look like a dumbed-down joke). A silly undercurrent is fine at times as long as it doesn't undermine the magnificence of human accomplishment that Civ (as an aspirational what-if historical game) is all about.
What gravitas there is in Civ VI (not much) is undermined by the casual cheap jokes and cynicism of Civ VI quotes, the smudged and muted leader backgrounds, the repeated and one-sided agendas (Civ IV's leaders had far more depth, as they had a gradiant of preferences on anything from trade willingness to the length of wars they would normally tolerate).
And there were missed opportunities, not just to have better menus, less toy-like unit icons, or suchlike, but to have more cool "new era" screens (like those of Civ V, accompanied by appropriate sounds, quotes, etc.--in Civ VI, they launch right into the bonuses and there are no historic quotes).
