What is so bad about them? I actually wanted those, but sadly missed this offer :(
My guess is that the evil ex-FLOTUS here is either:
a. Totally not a fan of first-person horror games, or
b. Reluctant to link her Humble and Steam accounts.
Apropos of the latter, I've got some doubts: is the link permanent, much like the GOG Connect one? Or you can unlink them at any time? (not that Humble/IGN won't remember anyway...)
Also, what happens when you reveal the Steam key that comes with a Humble game? Is it automatically redeemed in your still account, or can you just copy-paste it and do as you see fit with it like before?
It is definitely NOT auto redeemed. In the old days (two or so years ago?) there was an auth link, where you could only redeem on account without actually seeing the key, later to become an optional feature to auto-redeem if you wish. But later on Steam disabled this feature.
I know at IndieGala you can always unlink your steam, also on Groupees. Gog is somewhat unique, as their offer has legitimate reasons to be so.
edit: removed ninjad data