This is valid feedback and something for Walter to consider. I don't know how much access there is to the code around this, but it's possible that it can be tweaked so that the AI is less willing to provide gifts, and making even making more of a diplomatic penalty for asking. But it's more conducive to offer these things a feedback on what can be improved rather than make a blanket statement that things today are too easy.
If my perspective is of any value here, I used to dislike this mildly and saw it as a cheap exploit to "fix" (that is, that you can simply fleece pleased/friendly Civs for money or resources and there is no penalty or drawback for doing so), but these days I don't see it that way. For one thing, you actually have to have good relations with said Civ in the first place, and with the several maluses to relations incurred both passively and actively which the player is routinely confronted with (for declaring war on friends,
not joining in declaring war on enemies, following a different religion, refusing to adopt a preferred civic, etc.) this is not so easily achieved, and careless diplomacy often results in cautious and annoyed relations with most of the world, making this action a demand with a further penalty rather than a request without one. Secondly, there is also a small opportunity cost in the form of requesting too large a gift being refused, and some kind of hidden timer where they won't accept these back to back anyway. (For instance, if a pleased Civ has 600 gold and I request all of it, they will almost always refuse this, and it will be some time before they will give me anything at all, going forward.)
I actually quite like the passive and "consequential" modifiers to relations, but if anything could be fixed, the direct solicitations to immediately declare war, change governments or stop trading with major partners carte blanche should be removed. They're annoying and seldom offer the player any interesting choices: instead, it's almost never in your interest to oblige these, and they simply constitute a further drain on relations without a positive counterpart. Some other mods had a "Please leave us alone" option you could apply which would block this, so I wonder if it is something that could be incorporated into RI?
I definitely fear war, and much of my gameplay revolves around discouraging it. But not all players want this experience of being constantly afraid and being threatened with extinction. Many enjoy a more lax game that revolves around diplomacy and empire management. That's why the difficulty levels exist, so the base game (in this case, I think, balanced for monarch) offers a relatively tame and balanced experience, and it can become more difficult/threatening as you raise the difficulty level.
Some level of challenge where I feel rewarded for succeeding is desirable, and where I will be punished for careless or lazy playing, but that's (subjectively) very much a "sweet spot" and I don't want it to feel brutal, especially in a game where I enjoy playing through the full timeline and which takes tens of hours to complete. At this difficulty level, I often am at or near the top for most of the game, but it's not uncommon to be knocked off the high-horse, and surprise invasions of weak points of my empire are satisfyingly not uncommon. (Curiously, these invasions often happen even in the ancient era, right up to the current version, so I am missing what is so magical about 3.4 in this regard - and I've been playing RI extensively since 3.55

)
Aside from the matrix of "winning and losing" itself, it's also fun to see how the game develops organically. I like to see how and in what way the land gets settled: who takes the especially good land and how borders seal up; what regions become intense battlefields for centuries, and just generally how the political geography manifests dynamically from game to game. It makes it feel like I'm in some kind of historically plausible alternate world which is fun simply to participate in as its shape and character unfolds, with the challenge and desire to win layered over it. The aspect of the rich and beautiful art and flavor adds significantly to this feeling of immersion, as do the several ways in which this mod tailors towards a more authentic experience of real empire building without changing its core as an abstracted 4X game.
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Unrelated question, but how do you all feel about reloading saves to salvage a mistake? I absolutely cannot do it... I rolled an excellent map in a new game, and DoWd Arabia for a second city location that they were about to take, but I hadn't seen that they had an archer two tiles away from my capital just after moving my garrison one tempo away, so that I would have effectively lost the game without a reload. I reloaded it, and everything else was fine and the war otherwise was sensible, but now I just feel like that game is ruined and I can't go back to it with proper enjoyment anymore. The only time I ever reload is when there is a crash outside of my control, or for a legitimate misclick, but never from a deliberate decision I made. Does anyone else feel this way?