I like them on - they look kind of quirky and old fashioned. But if the the guitar hasn't got one on and no holes I say leave it that way - leave it naked, just as it was born.
I also like the look with pickguard better, especially when the pickups don't have covers. By the way, I remember Gary Moore's Les Paul (that he got from Peter Green) has a severely damaged top where the pickguard normally protects it.
Ha, ok! Seems like a nice split. I must admit I do like it on, it seems to make the guitar look bigger and better balanced in my opinion and it's a classic look.
I do feel a shudder though at drilling into my baby to put it on.......