The spin on fifth edition dungeons and dragons is the modularity component. Ie, you (which actually means, the GM (so if that's not you, you choose nothing)) choose the components of the game.
The fact is though, this means there will be about 100 games (probably far more) all calling themselves D&D 5E.
Lets say your own preferred game is at position 46 on the spectrum. The further you go up or down, the more it's like wearing a shoe which is not your size - either it's loose and comes off unexpectedly, or it's painfully tight and it's a fight between the shoe remaining the size it is and your own pain tolerance as your foot will not change size, of course!
Really D&D has always been like this, but as you got to third and fourth, it actually started to focus. Maybe a spectrum of about 20 game types.
But now this takes us back and this is part of why roleplay is so niche - the player base is absolutely fragmented. No one can really play with anyone else, because they are all playing one of the 99 other variants that still all call themselves D&D. It's like calling pizza and roast beef the same name - it ends up a bait and switch (except for the niche who ultimate get the thing they wanted - and the small size of that niche is partly why the RP hobby is so small)
Not to mention how that shuns any new blood. Having the game be around 100 games yet all share the same name means a potential new gamer who'd like game variant #33 has a 1 in 100 chance of bumping into that on his first game. He or she will associate D&D as being some other thing that they don't like, DESPITE the supposed wonderfulness of modularity. Oh, you could make just the game he likes with modularity, thus modularity is great? No, it means there will be 100 game iterations out there and he'll run into one he does not like. He will not try again (or wont try over and over and over, anyway). Modularity blocks out people, it does not include them!
The only person it includes is the GM who buys it and then makes a game which is incredibly specific to them. Maybe you haven't roleplayed before, but you kinda heard that there are dungeons, and dragons, and rogues and lots of battles. Okay, this sounds kind of interesting to you. You turn up and...actually your all plant people having courtly discussions whilst floating in clouds. Don't be silly, it's obvious that Plant people don't have rogues amongst them!
Such is the plant person scenario just swimmingly perfect for some dude out there (he will say "How D&D was meant to be!"). And exactly as it's customised to one person, the more it's a complete non fit to another. The more you customise, the more it wont fit other people - that isn't even a controversial proposition, just boring common sense!
The modularity will just make a disjunct between the advertising (by word of mouth or whatever) and what the person encounters on joining a game (unless they get really lucky and land in a game that modular choices actually align with what they want).
The new person wont see some wonder of modularity. They will just see (most likely) something they didn't actually come for. And they will assume THAT is D&D in its entirety - that it advertises itself as one thing, but does another that they weren't interested in doing.