As a DM, I present these options to players, and they're more inclined to go for the Core rules (either because they're min-maxers, care more about their character than the rules themselves, or have vanilla gaming tastes), or might nudge some WotC splat.
As a Player, I more often than not find DMs who want just Core only, or even if they allow other options, will allow a few splats. 3rd party stuff? That's broken, or doesn't fit their game, or they just don't own the book.
So, I end up with a player-focused product that I can neither get my players to use, nor get to play myself.
Anyone else find themselves in the same problem?
Who do you think you are? ME?
I've posted about this so often, it should be in my sig. I've been in this state since 3Ed rolled out. I've bought a host of 3PP, almost all of which goes unused.
I'm one of only 2 DMs in the group who uses 3PP- really anything significant beyond Core + Completes- and almost none of my players takes even a sniff of the non-WotC stuff.
IOW, several of my compatriot gamers- like them though I do- could reasonably be described as sticks in the proverbial mud.
Some of them have not and never will play anything but D&D. Not even other FRPGs. I'm not talking about n00bs, either- I've gamed with at least one since 1985.
Seriously, take them out of their comfort zone.
I've spent 2 years designing a post-apocalyptic homebrew fantasy setting. One of the first things I noticed as I was designing it was that if I eliminated Humans (as I had planned), I wouldn't have any players.
Its good to get your players out of their comfort zone, but if you try to take them too far, they won't follow.