True, I hate how game developers think taking shots at a person people dont like some how is an asset to their game. Personally I dont think there should even be a place for it, I rather them spend their time on the actual characters of the game.
To be fair, his character works perfectly even if people don't know who he is. If it wasn't for Rump, we'd have another character who'd be the corrupt, sleazy, megalomaniac major to fill that roll. So it's not like you'd need any kind of knowledge, if you have it it's just a little extra. In the end it's not like DC adds these characters as additional assets, but they usually fill roles which would have to be filled anyway. With some minor exceptions here and there, maybe.
Rump is actually among the parody characters I mind the least, while there are some others who I personally wouldn't have added.