It's not that I CAN'T play fast, dance stuff ... it's just that, I prefer NOT to play some of it. I've found that only senior crowds accept the electric slide as a live rendition. Most younger dancers are kinda snobby with some of the dance stuff, so why stir the pot? Most of those songs are not very high in content anyway ... they're just dance beats with stupid lyrics - I've had enough of that over the years.
I'd rather play the juicy, tasty stuff live, take the requests, personalize them, and switch hats to Mr DJ-guy when appropriate. That way the crowd is happy - I'm happy and I get re-booked.
I don't think there is any difference in using an audio file to augment my performance, than using a drum beat or arranger pattern. Either way - I'm the MC, I'm the tempo controller, I'm the set coordinator, party planner, cheerleader, band leader etc.
I'll use any way available to please my clients .... (except show reality TV)