3480665
Although I only read FiMFiction printed in dead tree format (99.9% of the time, I think I read maybe two short stories that weren't in a printed anthology) I do skim the splash page every time I drop by. I glance at the tags but I don't use them to find stuff. As you said, FiMFiction is starved for tags.

3480574
Yeah, this site is definitely starving for tags, and there is bunch of those weird crossover tags as well; many of them don't feel like they really deserve their place. (at expense of other tags)
For example: why do we have a Half-Life tag? I love Half-Life! But there are barely any stories written about it.
I think Knighty would probably be the best to make the requests to, but they don't seem to be very active these days as far as I have seen.

3480480
No, not often. I don't know where to make any such official request (Knighty? are they still around?). A World Building tag would be nice, and a tag for whatever it's called when you fill in the blanks between episodes... But really, no poetry tags at all? That's a pretty huge blind spot. Anyway I figure the omissions had to be stated in case anypony with the wherewithal to add tags was reading.

Do you make tag suggestions often? I noticed you made bunch of them on horror and poetry contests.

3119421
Just ran into you. Didn't know you tried to reply to me. 🙃

Anytime, bud! Always here if you need a friend ;3