whats so great about fire/kins?

Lewis sums it up well (although it should be mentioned fire/kins can get mez protection with IW and perma it with IOs, psi tornado being a good AoE as well).

The thing with fire/kin is it's really a tremendous powerhouse, so even if you play it poorly like 99% of the fire/kin players out there, you're still going to have relatively good results. That's the appeal for most people, I think.

It's also fast as soon as level 1 and can make an efficient ST damage specialist/AV soloer while not compromising AoE power if you actually pick and slot RoF for damage, but there's like 1 in 1 million who actually gets that.