MarioMeteor
Smash Hero
I like how you spelled Tatsumaki Senpuukyaku correctly while misspelling Hadouken twice.After some testing...Yeah don't use Sakunetsu Haduken on Bowser. Everyone else seems to be fair game though. There could be some moves that a character can use to get heavy armour, but I think more often than not you're probably dealing with super armour instead, and either way you could punish players for that anyway, so I'm going to stand by my opinion that Sakunetsu Haduken is at useful enough to put in the effort. (Unless you are afraid of accidentally doing a Shoryuken or a backwards Tatsumaki Senpukyaku instead.)
Anyway, there are only two situations in which Shakunetsu would be a better option than Hadouken: against another Ryu and against someone who likes to shield. Other than that, the difference between the two is miniscule, so you might as well go for Hadouken.