Yes. All the time.
First drama I watched, only did it because of Kim Ha Neul, 2nd drama was because of Song Joong Ki, then it was Ha Ji Won, etc etc, even now that I've watched so "many" dramas, I still do this. Only reason I gave Gu Family Book a chance was because of Lee Seung Gi.
I end up doing this all the time. I find a drama I like, then check the actor/actress out here on MDL and go through their list of dramas and movies and start watching those, until someone else catches my eye.
Yes. I've watched a few dramas because of Jang Geun Suk, Kim Jae Won, Yoochun, Song Joong Ki, Mukai Osamu and a lot more and it keeps on growing simply because there are a lot of eye candies in dramaland. XD
I started almost all the dramas I watched because various of my favorite actors were in them. Usually I start liking them after a while or drop them if I don't, though.
I really forced my way through "Muscle Girl" only for Lee Hong Ki, though. ;)