There are only a few that don't seem really gimmicky to me. I have the Korean BBQ now, have used it once and I really liked how it worked and felt like I got some unique flavor with that cooking method. I have used the sear grate once and it's OK. I don't know why the holes are so huge. My steaks got like 2 marks per steak. If they redesigned it with straight bars closer together I would ditch the old one.
I don't agree with the complaints about the size. The hole is 12" so that leaves a 5" strip around it. That is really narrow. But they're trying to keep part of your grill surface available on a 22.5. Any less room around the insert and you might as well not have the space there, you could just go full cast-iron. The Korean dome is probably not big enough to cook for a big party in a timely fashion but any bigger and it'd kill the utility of the rest of the system IMO. If you're serving as you go, then there's no problem.
I wish all of them were just cast iron rather than porcelain coated.
I think the griddle sounds really cool. I'd be interested to try a hybrid high-heat smash burger / grilled burger hybrid.
The hole seems perfect for a wok but I would just use a regular wok on it.
Everything else seems to only make sense for a gasser (ebelskiver, some of those EU-only ones) or are just gimmicks to expand the product line and would work better as a standalone pan like TheDude said.