Cho'Gath has 80 bonus magic damage per hit, a 650 true damage nuke, the highest base AD in the game and a LOT of CC, (that's without a single damage item, usually you will see Cho Building RoA/Rylais/IBG/Wits End) he doesn't get ignored at all, he gets all his skills dodged and then endlessly kited though, but that's the point, he's an astoundingly strong character, who MUST be dealt with in some way that doesn't involve getting hit by him, like a raidboss.
In fact, he demands a lot of attention despite being a huge wall of impossible-to-kill that's why his late is so awesome.
He does have a problem with the reliability of his CC, but Cho'Gath should NOT be your main initiator, he's great for follow-up for an initiation or counter-initiation.
Besides, being huge is a great way to nullify the effect a pick comp has on your team, since you're likely to be hit by most morganas bindings, blitz/thresh hooks and so on, which is often inconsequential since your main cc counterinitiation skill is ranged anyways.
Cho'Gath was hit severely hard by the unwarranted BoTRK buff, the Randuins nerf, and basically the huge mess that the ADC update was, but he remains a strong champ.