There is no other late night host that can do "history of rap" OR "evolution of hip hop dancing", to name a few. So I would highly disagree with the "least talented" angle.
He is certainly leaps and bounds better and more talented than Conan ^_^
Considering his entire comedy skill set, Fallon probably is more talented than Conan (Conan is purely a writer with a few physical bits that he can lean on. If he has anything over Fallon, I'd say he has a sharper wit).
Fallon is just a better overall host for a late night program. I wouldn't call him leaps and bounds better, but Fallon "fits the mold" better. In a way, I think NBC realized this when Conan went to the Tonight Show, and I dare say the comparison had something to do with that embarrassing ouster. Leno is a dick, obviously, but after watching more of Fallon in that slot, as that was all happening, I kinda think that something else was afoot beyond Leno simply being king ass.