I prefer the sound of an acoustic instrument through a mic if some amplification is needed, and it usually is, but it seems that bluegrass festivals are the only place you'll see this these days. I remember the first time I saw/heard Doc Watson plugged in. I hated it. It sounded like he was playing an electric guitar. As "acoustic" pick-ups improved, Doc eventually sounded like the old Doc Watson.
At most venues these days sound techs will say,"Why are you using a mic? Don't you have a pick-up?"
I now have pick-ups in all of my guitars. One has a first generation Fishman under-saddle that used to have a "quacky" sound, but these days the sound techs seem to be able to EQ it.

Someone above put guitars with pick-ups into three categories: solid body electrics, hollow, or semi-hollow body electrics and acoustics with pick-ups. Better categories would be guitars with magnetic pick-ups (the electric guitar sound) and guitars with piezo (or whatever they use nowadays) which give the "sorta acoustic" sound. An acoustic flat top, like the D-28 Gabor Szabo used with a magnetic deArmond pick-up, sounds like an electric guitar, while a solid body Godin with an "acoustic pick-up" on the bridge gives the "acoustic" sound. Because I agree with the purists to some degree, I have tried to use quotation marks around the word acoustic when I mean amplified acoustic.

I would love to play with only a mic all the time, but when others are plugged in, the balance is never right unless I too, am plugged.