Plating is quite a big part of cooking. Things that look attractive tend to taste better as well.
Personally, I find artistic plating quite a challenge. Part of the problem is my lack of artistic skill. But there are pragmatic concerns too.
For one, fancy plating usually works better when the plate is really large. But, for everyday meals, I use everyday plates. (I only own one or two large items that I would still consider plates rather than serving platters.) I'm not going to buy another six or eight large plates just for the sake of being able to spread the food around a bit more. Cupboard space is always at a premium.
Another problem is the time factor. When I cook and want to bring, say, three different things together at the same time to plate them up, I don't want to spend five minutes standing there in order to arrange the food onto three or four plates, only to let it get cold. In a commercial kitchen, there are usually several people involved, so one person can focus pretty much on the plating. Moreover, the arrangement is known in advance and plating means putting the food onto the plate following a known plan, as opposed to me standing there and scratching my head and wondering "how can I put this together so it looks good?"
Finally, in a domestic kitchen, individual pieces of meat or fish rarely have the same size and shape, which adds to the problem. In a restaurant, very often, things are cut to size in advance so they are all the same and there are no surprises when plating; the off-cuts make their way into other dishes. At home, this just isn't feasible (at least not for me).