The nerf hit him hard. He still has use: he didn't lose damage, it's just harder to properly maximize since he doesn't lead into his chase. He still has his dodge. He lost the revive/cleanse in favor of a chakra battery mechanic.

On one hand, it's nice to give players who dont want to play chakra gaining mains (and don't have ninjas like sage naruto, asuma, mabui, etc.) a "free" method for chakra acceleration. On the other, he's just not very good outside of that - and if you are running nukers you want a ninja that can offer more than that extra chakra. Heals, shields, buffs, clones, etc. Tobi's damage/ignition just isn't really worth it compared to other ninjas that give chakra.

In a nutshell, by the time you can see and recognize his merits - you'll be ready for someone that does what he can do much better.