Thank you.
I've ran some numbers myself, since actual game experience is considered too anecdotal.
Note: I've left crits out for simplicity and assumed Human so he can get all his feats and +5 ability score by level 8.
That's a fatal flaw - Crits really skew the numbers (in favor of the feat)... Especially since it's just +(0.05*(avgOnDamageDie)) DPA.
Your numbers are flawed by virtue of (1) selection bias & (2) small sample.
In the range of typical AC's (13-18 for most monsters) you're better with the attribute raise than a power attack feat.
Bless effectively shifts the expected range to 10-16.
Yes, Bless is a potential problem. But bless is limited uses - so if it's dominating, the solution is not to nerf the feat (which is, most of the time, inferior to or only barely better than the attribute raise it replaces); the proper solution is to nerf the caster of Bless - and as with all non-warlock spell casters - which is done by forcing them to use spells before the bigbad. And remember the time limits.
Don't give them a break between the battles - as they're finishing up wave 1, wave 2 shows up.
Use dispel magic on blessed foes.
Occasionally, have a fallback-engagement... where the badguys are in range, but never close to melee, and retreat when PC's try.
See if you can split the party.
On the other hand, D&D is (and has been since early on) Medieval Super Heroes. Just look at the fighter level titles in the little brown/white books...
1 | Veteran |
2 | Warrior |
3 | Swordsman |
4 | Hero* |
5 | Swashbuckler |
6 | Myrmidon** |
7 | Champion |
8 | Superhero |
9 | Lord |
Feats need to be power climb. Spells need to be power climb, too. But the power climb of the power attack feats is NOT gained when the needed rolls are around 15's, ±(1 to 2), widest for the strongest. (Which, for a 1st level party, is AC 18-22, for needed TH rolls of 13-18).
And, while I don't have roll logs (I don't play online, because my experieces with D&D online play are EXCEEDINGLY negative due to living up to bad D&D player stereotypes), my experiences with 30+ sessions with people using power attacks, even those who have a clue haven't done the math, and make suboptimal choices (giving up chance to hit 3-4 turns running). And, I should rerun them accounting for advantage - which at my table is far more rare than Bardic Inspiration... I've only had bless cast once, and I will admit that I've never DM'd a 5E party above 8th level. But, at least in the 4th-8th range, it's been consistently misused.