I expect it to be a buggy mess that has lots of potential and doesn’t deliver on half of what it seems like it should do. Then after a year or two it will finally be patched into being mostly stable and mods will have reached a point where it can mostly be turned into the game I actually want. However there will be a few creative decisions that I absolutely hate but which are so unnecessarily locked in that even mods can’t fix them, so I’ll have to just accept them as an irritant that I will do my best to ignore.
This argument just dismisses all criticism of the rules and implies that the “game” portion of the role-playing game is irrelevant. By that logic, the design of D&D 5e (and every single rule and mechanic in it) is no better or worse than any other game, including stuff like F.A.T.A.L.
If the rules don’t matter, why bother? Why buy books, learn a whole system, and go through the effort of trying to use a specific RPG instead of just doing free form role-play?
If they do matter, then they can and will impact the quality of your experience in positive and negative ways. They can be well designed, easy to understand, and effective at serving their purpose, or they can be poorly designed, incomplete, confusing or nonfunctional.
Sure, you can ignore rules when you don’t want to follow them, and you can do your own thing and homebrew it if you like. You can also ignore the ending of a book and write your own headcanon, that doesn’t mean that there isn’t any point in criticizing bad writing.
To put this another way, why have rule books and a character sheet with all those numbers on it? Why not just flip a coin whenever you want uncertainty about an outcome? Would a game with only that mechanic be just as effective as D&D at providing the type of experience that D&D is trying to create? If not, then why not? What makes the big complicated mess of rules that is D&D better than my single rule RPG?