The FR logo has actually pushed me away from buying quite a few products over the years.
I got the 1e Grey Box, and it was awesome. Then everything else... more or less ripped off (or "homaged", if you're feeling generous) pretty much every fantasy trope. Stole mainstream stuff and shoved it into an FR-labeled envelope (Monsters of Faerun, I'm looking you right in the eyes.) As time passed, more and more stuff got shoehorned into Realms books that was really intended for every D&D game (hi there swordmage!). I am so sick of it that I could vomit.
If the 3e Underdark book hadn't had the FR 'brand' on it, I would have grabbed it in a red-hot second. Likewise, Serpent Kingdoms, Monsters of Faerun, Champions of Ruin, etc.
Is "Oh, it's an FR product" a good reason to skip a good sourcebook? NO- but, inevitably, I end up doing so anyway, because that's how strong my antipathy towards the Forgotten Realms is. I almost bought the 3e FRCS book; it was fantastic, but I always turned aside from it in favor of, well, anything- 3rd party products, the Eberron setting book, beer, porn, giving my money away to a homeless guy.
The FR brand is a HUGE turnoff to me. I hope to God that WotC doesn't put ONE. DAMN. REFERENCE. to it in DnDN, except in FR books. I do not want a single tiny drop of Realms garbage to get on the other books on my shelf.
In fact, putting the level of FR support in 5e's PH that Greyhawk saw in 3e would be too much for my tastes- I DO NOT WANT Realmsian deities listed in the PH or Basic Set or whatever it ends up being. I DO NOT WANT references to Amn and Cormyr as 'assumed setting elements'.
As far as I can come up with, FR support in the core rules is about the only thing that might push me away from buying 5e. Is that stupid? Probably, but it IS. I HATE the Realms, with all its damned DMPCs and ridiculous, flavorless, mashed-together nonsense, enough that it might be a dealbreaker for me. I really really really really really REALLY hope that the "early support of FR" we've heard about for DnDN/5e/whatever is not in the generic rulebooks. I want a system that supports MY HOMEBREW, NOT ED GREENWOOD'S.