That all depends on your individual group, I think. I know I actually spend my feats on Toughness, Skill Focus, Alertness, and such. I kinda don't want my mages to die from Random Goblin-Child Thrown Rock #3 That Happened To Crit, or Minor Orc Axe Hit #1 That My Stupid Fighter Companion Didn't Bother Getting In The Way Of, or my rogues to botch a Listen check to avoid being bushwhacked when they're scouting, or what have you....
I've seen players take feats like Toughness and Skill Focus, including myself. Of course they won't bother if you start them out at level 5 or 10 or somesuch, when the benefit is negligable.
Anyway, I've finally pinned down a fair way to handle those feats in Aurelia, so at least in my next campaign, players may seriously consider beefing up their survivability with Toughness or beefing up their skill prowess with Skill Focus. I changed skill focus to not only a +3 bonus, but also 1 free rank, and another free rank at 10th-level. I might add a Greater Skill Focus feat at some point as well....
Though I had already HR'd Toughness to give 4 HP, I decided to add that its effect doubles at 10th-level onward. So if taken at 1st-level, it'll give 'em 4 HP, but then that same feat will improve to 8 HP later on so the PC effectively gains 2 wizardly hit dice in equivalence (or 1 monkish hit die in equivalence). Still available multiple times. So if some human took Toughness twice at 1st, once more at 3rd, 6th, and 9th, they'd end up with 40 extra HP by 10th-level, a huge boost for a mage or rogue type. Not like they don't get a few bonus feats anyway in Aurelia.... And of course there's the other Toughness feats of Aurelia, being Improved, Greater, and Superior, each requiring a few other Toughness feats and giving a bigger boost to HP.