Every single tile makes a difference. But only if they're different.
I might end up wanting to settle next to the mountain not because I'm next to the mountain, but because of the combination of a) the river touches there, b) it lets me reach a good campus spot, c) it is more defensible, and d) I get to control a mountain pass.
Now, the same might happen for settling on a coastal tile. However, there are also *consistent* negatives for founding on the coast. These will rarely be overcome, since there are so many of them and (so far) so few positives.
1) You have fewer tiles to build districts on. (each tile you settle closer to the coast is another whole ring of water tiles)
2) You have fewer workable tiles. The water tiles basically don't even count as workable, since their base yields suck and they aren't improvable, even by the normal water improvement buildings we've seen.
3) A coastal City Center appears to provide no benefit (except anti-siege). You can't construct naval buildings (still need a harbor), you don't get a bonus to trade (still need the harbor), and naval units appear to be pretty useless (if nobody else has a reason to build/trade on the coast, navies suck again).
4) There are some things that could still be revealed to be of use, of course. Perhaps the appeal of the city center matters, and coastal tiles have more appeal. Maybe the city automatically gets a trade route for being on the coast, so it can get up to 3 by building a harbor and commercial hub. Maybe there are many things that make it worthwhile! But we haven't seen any yet.
So yes, we are trading a single choice (found on coast or far inland) for more options (on coast, sorta on coast, inland). But at the same time, the on coast option seems to be nearly strictly worse than sorta on coast, which makes it not a real option. It needs something to make it more worthwhile than currently, especially because coastal cities are such a huge part of real civilizations (I'm not saying flavor is everything, I'm saying its intuitive to make coastal cities an actual option).
This "choice" you guys are worried about isn't gone though. Its just been shifted from where to settle to what districts you want to build. Sure, you can get a navy and sea trade with a city that's inland a bit but at what cost? Your industrial district? Science? Religious? How long do you wait to build that first trireme and how many beakers do you have to dump into naval techs to catch up with those that snagged early Eurekas? Until your first or second city hits 6, 9 or 12 pop?
No, here's the problem.
What good is sea trade? We've seen no reason to believe its worth anything more than land. Perhaps even less, since it doesn't make roads.
What good is the navy? No trade to control. If there's no trade to control AND sea tiles absolutely suck, nobody is going to build on the coast. If they want a navy at all, they'll found inland. So if there is no trade to control, no sea tiles worth blockading, and cities aren't in reach to attack with navies, what good is a navy?
What good are naval techs if the navy and sea suck? Why do I care about those eurekas at all? I'm not missing anything by waiting for those techs.
This is looking more and more like a false dilemma. "Oh no! We're not forced to settle subpar cities in order to engage in the naval game!" It really wasn't a choice before. I had hoped my first post got that through. "Either you want a navy or you don't, now settle accordingly," that was the "choice" that's being taken away from us.
There was a reason to settle on the coast before. It enabled sea routes which were better than land routes, and sea tiles could be at least passable.
Because there was a reason to settle on the coast and protect the coast, there was a purpose for navies. Thus, even more reason to settle on the coast.
There is no reason for any of that currently. The choice is actually being taken away, because the naval game has not been shown to exist at all. Just found inland always! Even if you do want a coastal city for some niche reason, it might as well be inland! You still need the harbor to make any of the naval buildings anyway...