Nymus

This is more of a question than a suggestion really, I'm a pretty casual fan without an in-depth understanding of all the units or competitive balance so forgive me if this is a question with an obvious answer.

After looking through the units pages for the four factions I'm wondering why there isn't a unit similar to the Siege Chopper in concept. (Unless I missed one?) I thought that the trade off between being able to reach favorable positioning while flying and highly mobile on the one hand and having to be grounded and risk being vulnerable while deploying/undeploying in order to siege on the other created interesting tactical applications. Was that a bad idea because of balance or what?

I had fun with Siege Choppers and I would like to use something with the same basic idea, a flying artillery unit that needs to deploy in order to siege.