One of my favorite parts of being a dad is the wrestling. We set up the octagon in the living room and lay down some ground rules (stay away from the face, mom is fair game only if she stops in the middle), and then proceed to forget the rules and have a match that would make rugby players grimace.
Turns out, that's a good thing. Not just the time spent with dad--which is huge--but physical play and roughhousing is, according to a study, good for child development. There are a good deal of neural connections being tested and established during this play, including understanding what the body can do physically, what getting thrown around feels like, and building a level of trust between parent and child.
Keep on roughhousing, people. Your kids' social and mental development depends a great deal on it!