1. All this seems to highly depend on how many groups adopt the updated ruleset. Like if everyone is using the new rules great! If it's 50-50 then buying the new rulebook may mean you bought the wrong D&D to be able to play with your friends - and there's a good chance you wouldn't even know to ask the question about whether it's the right version or not as you are new.
Okay, how do you imagine that conversation going?
For me, I see something like the new player bringing out their book... and the person with the old rules immediately identifying it and telling them they would prefer to use the older rules that they have, and here is their book.
Or I see the new player going through their character creation and the mentioning that they picked the pike for their Weapon Mastery... and the person with the old rules identifying that those rules aren't in their book, realizing the other player is using new rules, explain they would prefer to use the older rules, and here is their book.
At any functional table I can imagine, this is a brief hiccup, and if the book was clearly labeled 5.5 edition not 5e edition.... the exact same thing would happen anyways. So the branding on the books is not making a difference here, and any confusion i minor at best.
2. And on the other side let's say you have someone casually into D&D that occasionally buys some books. If they walk into the same store and see a D&D players handbook or even Revised 5e D&D Player's Handbook - they are going to think I already own that, why even look at it.
You... realize they will have different cover art, right?
But fine, let us assume that this person who casually buys DnD books walks in the store, sees the Revised PHB and doesn't buy it because they think it is the same book. Are they harmed by this decision? Will they suffer any negative consequences? Let us say they two weeks later run into a DM who demands that they immediately procure the newest rulebook or face the Rod of Beatings... they can just go back to the store and buy the book, now that they know it is a different book.
And how would seeing "Revised Player's Handbook" NOT clue them in that it is different than the Player's Handbook back home? Even if they look at it and assume the book is only midly different, if they are in a brick and mortar store.... they can pick up the book, flip it open, and see the changes for themselves. That's what I would be likely to do.
At the end of the day it seems better to call it something clearly distinct while marketing it's compatibility with existing 5e products (even if a little rough around the edges in some cases).
Okay, but if is clearly distinct from DnD 5e, the game that the blind customer was interested in, or the game that the casual player already has, then doesn't that make them just as likely to pass it by? This doesn't actually prevent the non-problems you pointed out.
