I why certain characters frequently pop up are the result of a number of things:

- Brand recognition. Certain characters have to reappear. They get chosen b/c Hasbro wants to develop them and build them into brands.

- The writers. A lot of them do a bit of research and the ones that stand out to them are the more special ones. Blurr always had a speed factor, unique style of speaking. Swindle as you've noted was one of hte more standout Combaticons. Remember that episode where he tries to bargain with Galvatron? That moment was ingrained in my mind b/c of his sheer audacity. Blitzwing is similar. He was featured more in G1 than say Octane. And if I was going to pick a triple changer, the best for the Animated role with the colour scheme in mind was Blitzwing. So these guys, running through TF history, pick up guys that stand out or have potential to them.

For this reason, I don't think the Unicron Trilogy characters will ever have the same focus. They weren't created for an American/Western audience. They were for Japanese audiences and the I don't think they resonate well with writers who go back and look for ideas.

- Story need: For balance, certain characters are always needed. Starscream's a perfect example of this and why will he be one of top several transformers. Cyclonus doesn't come up often surprisingly enough b/c in terms of loyalty he was the one who had it. I guess the problem with him is he is more closely associated with Galvatron and given the lead villain is Megatron, that makes sense why Cyclonus has had little air time.