On the use of body_class, comment_class, and so on

Hi there,

I have been looking but haven’t found a definite answer to this. Basically, we are developing some themes and stumbled into parts of the templates that invoke the css class-adding functions, such as body_class, post_class, comment_class… you get the idea.

My question is, is it alright or acceptable to avoid using those functions? since our theme is going to be designed from the ground up, it’s interfering with the kind of clean markup we want to achieve. We also wish to have control over what’s outputted as html, to make it more maintainable.

What problems could arise from not adding them? For what reasons are they used? What about plugin compatibility? Do they play an important role in that?

Thanks in advance.