I wouldnt't worry too much. Gear for the most part changes the looks drastically for a good % of the roster, take Sub for example you can make him look VASTLY different than his default design, I'm sure Raiden will be no different. We know the many designs of Raiden over the years so I have no doubt we can make him look like caped Raiden(which his render shows), no hat, different hat, no mask, normal shirt, MK 1, MK X, MKD etc, etc I don't think it's underwhelming, still a better system than lame variations where certain characters sucky presets or are disappointing. Bane has his comic book masks which look nothing like sea divers if you mod him with the right ones. FS doesn't look bad, but he doesn't look like FS. I think he should have had a classic skin honestly. I think Raiden will get the Sub treatment, he'll look mint when we get more gear. We have to remember he's an MK character and this is a NRS game. I doubt they'll punk him.
As for Spawn, I hope he gets in FP3 but if not I won't lose my shit over it. That's a big character so there's a lot of redtape to deal with.