There are no "real" limitations from this being the case - only if the players don't like it.

Kinda like if everyone sat down to play checkers and you started playing chess. Maybe everyone would love to play chess for a short change or maybe there's a reason they would rather play checkers; depends on the people and the game everyone agreed on and sat down to play.

I would argue that all the physical/visual flair is part of what has made D&D larger than ever. I do agree that it is still flair, and not necessary to run a game. That being said, I think there are individuals who do need the concrete "things" in front of them to immerse in the game, and a more visual map helps engage them. So, while I think it is not necessary for the game, I do think it can be necessary for some players to have a good time, and having a good time is what it's all about.

I've browsed through them a couple times trying to decide what I would get first... including this years

Pretty sure it's gonna be this years.

Very Nice. I can imagine flowy underwater vegetation, bits of shipwrecks, colorful coral decorations... I'm excited for this one.

I think one thing to keep in mind is that some maps could be pulled off just by applying a tint and effect over the whole map, if the whole thing is on the ocean floor or something - like this example I'm just pulling from Google.

One thing you could play with is adding sheet effects to the trees and land textures that desaturate them a bit. The Schley style is bright and colorful and by making those things a bit less saturated it might help them fade into a background while the rest that is bright becomes a foreground.