I'm not sure what a ficlet is. I'll assume that it's a short-short story; correct me if I'm wrong.
It's not a bad idea for a category. Last year, when I was trying to decide on URA categories on the discussion list, I considered having separate genres for types of fan fiction - drama, comedy, et cetera. I decided not to do that after all for several reasons. One, I haven't read anywhere near enough fanfic to know how much there was of each kind, and whether there'd be enough for this category or that. Two, when you start creating cats for fic, where do you stop? No matter where you do, there's going to be something covered and someone complaining about that. And on the gripping hand it would have added more work to the URA project than I wanted to put in, not only with counting votes but also making judgement calls as to whether this fic really belongs in this category, what to do for nominations split over categories, et cetera. It would have been more of a headache for me than it's worth. So, instead, I decided only to categorize fiction in terms of clear, easily quantifiable terms: single story, series, and MiSTing.
I think that if a ficlet is very good, it ought to be able to compete with the single stories. Size ain't everything, after all. A separate ficlet category - and categories for other types of fiction - would be a better idea for a fanfiction-specific award thing. I'd considered doing one, but after last year's URAs I decided I'd had enough for that year. It would be a good idea for anyone who wanted to take a project like that on themselves. I'd support it.