With the new change his ultimate can reasonably be expected to reach 1000 true damage too champions, and 1400 to monsters. At any point in the game, a cho ult can beat a smite at objective secure. It just seems really good to have all the objectives, and flash pop in and insta gib people.
His Jungle Clear is really slow. He does not have good ganks. The best junglers right now are early game dps junglers.
Why does he have to be a Jungler just because his Feast is better than smite?
You could play him top lane, mid lane, anywhere else, and still have more objective securing power than the Jungler.
In fact, it's probably better that way, because combining Cho'gath's feast with a Jungler's smite, gives your team an extra redundancy, when combining objective securing power. Which will make it more difficult for your opponent to secure objectives in a safe manor, without taking out both Cho, and your Jungler.
mainly because 
Same reason as before. Q is unreliable as initiation and no one in lane wants to play anything other than mega dps. So you get to 30 min mark and can't do anything
I've been thinking of cho jungle i've done it in the past to some success, but his early clears are really slow + mana intensive I am loving the ult changes though, 2100 free hp at 15 stacks, throw a titanic hydra in there and you will deal a lot of aoe damage on your AAs with that + E Maybe with a meta shift to more tank junglers (waden update?) he will be great, cinderhulk on him must be hilarious
"why isnt cho jungle common now?"
implies it was common before, but truth is cho jungle hasnt been common since like season 3.
