Microstock Categories - a help or hindrance?

I'm nowhere close to earning a decent income from microstock and doubt I ever will, but it has provided me with some great positives:

• I'm a much better photographer; I'm learning about what makes a 'commercial' shot, improving my understanding of composition and even starting to get my head around Photoshop
• It's a nice feeling that someone is willing to pay for my work
• I can (start to) justify spending money on new gear

What is frustrating though is the hassle (and therefore time) involved in the upload process to the various sites. Specifically, the insistence that alongside keywords, categories have to be specified. They either overlap with keywords, or the list of categories to choose from is so incomplete/patchy, there's never one which seems to fit. And as the category options are all different across sites, there's minimal opportunity to select generic categories.

I'm not a buyer from microstock sites, so would love to know how useful the categories are? My hunch would be though that most buyers know what they're after and they'll simply drop the relevant keywords into a search box. I guess microtock administrators can see from their web stats how often categories and used to search versus keywords, so I'd love to get an insight into this too...

So, I vote to remove categories from the microstock industry! Do you?