I personally hate oblique kicks and would cheer if they got banned.
As to spinning elbow, if done properly it shouldn't be illegal. The problem is, it's hard to hit with it, without hitting someone in the back of the head. Just look at the Jones vs. Bonnar fight. They actually even fucking promote that illegal/dirty hit even though it clearly hits Bonnar in the back of the head. But I guess it's too much to ask from the refs that they would actually notice things like that during a fast paced match.