I always thought the intent of the maneuver was to make 2w fighting viable. Of course I would allow it with 2w fighting as the only thing that matters in combat 80% of the time is forcing MDSs. Two-weapon fighting is just so awful in the game, unless, of course, you have a bunch of Sneak Attack damage, in which case ... you have a bunch of Sneak Attack damage and will kill everything anyway.
1st level dude with STR 18, war sword in one hand, shortsword in another
+5/5 to hit, ave. damage of 8.5 (6.5+4-2)/4.5 (4.5+2-2)
1st level dude with STR 18, greatsword or bardiche
+5 to hit, ave. damage of 16 (5.5+4.5+6)
w/Power Attack, +4 to hit, damage 18
Reduce STR to 14:
+3/+3 to hit, 9 damage
vs.
+3 to hit, 13 damage
6th level (all "fighter"), STR 18 (fairly normal at this point)
+10/+10/+5; 8.5/4.5/8.5 - barely a MDS
vs.
2h weapon, nothing special +10/+5; 16/16 - not a great chance for a MDS, but that's why people take Power Attack or have Sneak Attack
vs.
Combine Damage with one 2h weapon +10/+5; 14/14 - this is far, far better than 2w fighting
vs.
2h w/ PA and Cleave +6/+1; 24/24 - or however you want to scale it
Note that the first case requires all three attacks to hit. The fourth case, the typical Power Attacking fighter, needs only one hit to force a MDS and will likely Cleave for a free attack. The third case is interesting but not terribly exciting. Note that the fourth case is more likely to hit with its first attack, the only attack it needs to hit with, then the third case's combined attacks; again, the Cleaver will likely get a free +6 attack for another ~24 damage.
Reducing the STR below 18 makes the Combine Damage 2w fighting dude not even average a MDS.
Anyway, there are lots of other combinations of numbers, but the math in the game has always, in my experience, been in favor of Power Attack, Cleave, Reckless Attack (for overkill), Great Cleave (for annihilating anything within range).
As for Explosive Power, sure, it guarantees an explosion of an enemy. That happens virtually every time, anyway, in the game when you have someone with a high to very high STR, a 2h weapon, and Power Attack. You have to have a really specific scenario to where Explosive Power makes a difference.