Well, as KeratinPearls stated, you'll undoubtedly be looking through microscopes a lot during at least a few months during residency. After that, you can probably pretty much avoid it if you so choose (Just as you can choose to pretty much only do it exclusively).
I'd say it definitely helps to have an interest in it though because it really is a part of the field.
So as an example, if you're working in a private practice group, you may have a dedicated dermpath person who reads all the office slides. Alternatively, you may send your samples off to an outside dermpath. Can you get an impression of what's going on by cutting to the chase and reading the dermpath's final read? Yeah. Will you probably be a better dermatologist by really understanding the histology and maybe even going to sit in on some dermpath sign outs of your patients? Yeah.