Damn, was really hoping Level Up would sidestep the "Want to take a Feat, huh? Well how well did you roll at CharGen for starting stats?" problem. Leads me to couple questions that aren't exactly Feat related, but are relevant to the opportunity cost of taking Feats.
First, did Point Buy/Standard Array get bumped up to not be worse than average compared to rolling? If not I'm worried that more appealing Feats will lead to more rolling for stats, which results in either party members at fundamentally different levels of power throughout the campaign or "suspiciously" good rolled stats.
Second, speaking of starting stats, what was the assumption of party stats when developing the (fantastically thorough) Monster Math? Did it assume the PB/SA levels? If based on that, combined with reliably obtainable magic weapons, Feats will be a lot more appealing instead of feeling like shinies to distract you from that sweet sweet +5 Ability Modifier you should've rolled better for at the start of the campaign.
Concern about the o5e skeleton aside, Synergy Feats are cool as hell and I'm really looking forward to seeing that Untamed one