The issue with most rain gear is that you'll get just as wet and clammy inside of it (i.e., sweat from riding) as you would have been from the rain without it. If you're riding in cold downpours where hypothermia is a real danger then rain gear has some advantages... Otherwise... just ride.

I have ridden many, many miles over the years without rain gear, trash bags or anything. Just get wet.

If you're commuting in high-traffic areas, then lights or something for higher visibility is advised as motorists expect you even less when it's raining.