Let's see here...
You buy a modern realistic combat simulator game...
For which the great majority of mods are simply representations of real-world forces...
Expect, as a given right, for there to be support for anime-style warmechs in this game...
Despite your opinion being one of a tiny, miniscule minority in the game's playerbase...
And then state, when you discover that the expansion pack does not make modding said warmechs easier, that you will never buy another of the company's games?
I think you're expecting a little much mate. Just chill, enjoy the games for what they are, and if somebody makes a mech mod, woohoo.