I wouldn't really say we "dumb it down"...we play to our interest and our ability...JUST like the guys who did those Top 40 hits that so many bands like to cover. I would guess that you also try to play your best...original or cover.
Come on now...I know you're not going to say that most of the stuff you hear in bars is very difficult.

Sure, every once in awhile a band does some really difficult covers...and nail them! And that's impressive.
But most of that "party band" shit is nothing all that complicated, and I think any decent bunch of players could do it...just practice!
That's where I'm at...pulling out interesting covers that make people take notice.