The problem with FS3 is that the number of times you do actually have to roll is so small that any failure is magnified tremendously. If you only roll three times in a combat, even a single failure is going to make a "can't miss, hotshot badass" look "ho-hum". If the character is, by reading the sheet, supposed to be "ho-hum" that's not a problem. But when the character sheet reads "this guy is a veritable god of combat" failing even one out of three is pretty bad.
I think this is a really good observation, though I'm not sure how best to address it. FS3 dice are very forgiving until they're...randomly not, and there's sometimes just this 'Whelp, that weirdly happened' feel to Failure, rather than any kind of opportunity to make it fun and interesting. Maybe everyone should build in an RP Hook 'flaw' they could exploit to earn a Luck point in Failure situations? I don't know. They're rare enough that they should be cool/exploitable for some drama, not just 'huh, shrug, that dun work.'
This is more an issue in straight-up rolls, not so much opposed/+combat situations.