Good thing about using a soundhole pickup is that you don't need to cut your precious guitar to install the tone controls (even those with guitars below RM500 would feel pain just thinking about it)!

Soundhole pickups are also less suceptable to feedback and I heard they can be used more "forgivingly" in an electric guitar amp.

And it's cheaper too...

Of course, if you want to record all those nice "finger slide" or guitar body tapping type sounds, you'll need a built-in pickup...