The benefits of penis-typing far outweigh the drawback of it being slower. First of all, you're standing instead of sitting for hours. This is much more healthy. Standing desks are available as well. Second, it excorcises muscles that you normally dont use, and even strenghtens the penis itself. This actually aids in preventing erectile disfunction later in life.

There are special penis keyboards (penboards) on the market that have larger keys for this practice.