Why are gyrocopters so small?

I see that the Fairey Rotodyne had a max. gross weight of over
32,000 pounds. The only gyro in which I have time was close to
2% of that weight. It's been years since I've been to a PRA
fly-in, but I only recall seeing *little* (two-person max.)
aircraft - much lighter than the 5200 pound fixed-wing I'm
accustomed to flying.

I'm curious if there are special design problems that emerge
when gyros exceed some weight, or is it just that people who
want gyros don't want large aircraft?

Thank you.

--kyler