Could be, I mean it is beyond any shadow of a doubt true that people who were playing 3.x would have simply never even heard of, let alone cared one lick about, 4e if it had been published by "Giant Fantasy Brain Books" and was called "Heroic Adventures" or something. It would have sold the obligatory 3-5 thousand copies and gone right out of print, like 97% of all other heartbreakers. That's just the reality, TTRPG is a tiny industry which basically has room for one dominant product, which has ALWAYS been D&D, it got there first, and it is unlikely to ever be replaced in that spot, despite some people wishing the contrary. So, what pleased me immensely was being able to have a slightly different take on D&D that could actually be high enough profile that I could count on having players. Even today at least people know what it is and it's actually quite easy to find people to play with. None of that would be true for some off-brand version, nor would it have gotten 20+ supplements, etc.
And, honestly, 'legacy' TO ME is not much of a word. I have my Holme's Basic book, my LBBs and supplements, my 1e and 2e books, I can play those anytime I want. I don't need every new D&D game to slavishly stick to the letter of whatever was decreed in 1974 on the back of a napkin. So the entire argument that it is some 'betrayal' or something (note
@Imaro's statements) is ludicrous in my mind. WotC owes nothing to older editions, they stand on their own. Heck nowadays they'll even sell you PDFs of large parts of the TSR back catalog!