I don't find "lol 5% of the time something WACKY happens!" very fun very long, no. That is too high a frequency for freak events. Actually, it's 10% because people do wackiness on natural 1s and natural 20s. That's too much! That's so much it's distracting.

I outlined the dice system I liked from nWoD in another comment. You can get some wild outcomes there, but it's not the absurd flat "10% of every roll is insanely good or bad". You get the occasional "I can't believe I rolled three tens convinced the vampire I was a wizard!", still.