I think in my particular case it's more of a personality thing overall. I'm overly critical of everything I do, same as with my RP when I used to RP. Others could be wowed, but I'd always find them inadequate for some reason. 

 As for losing interest in an RP, that's another personality flaw of mine. I grow bored easily, and often want to move on to something else. That's probably the reason why I quit rping in general... being constantly overcritical of myself often had me cranking out unnecessary post lengths ( I'd say some would call it fluff? ) going beyond what was called for, and over time I'd grow bored with what I was doing since I had so many ideas I wanted to act on, but was never able to dedicate myself to any of them.