Why is the presentation separated into classes as well as templates?

If the presentation was located entirely in the templates I'm sure there would be a lot more skins contributed to the project.

If you hack a class to produce a certain look you cannot update B2evo without a lot of hassle. And you MUST hack a class if you are going to do even slight mods to the presentation of specific fields.

If you want to increase the number of contributed skins remove formatting from the classes and let the templates handle presentation.