Erm... I see you in Twitch stream chats all the time - are you watching the same games that I am? Brummbaer is the most efficient non-doctrinal late-game Ostheer unit, wiping infantry and support weapon teams left and right while USF/UKF AT guns struggle against it. It's more than fine the way it is.
UP with a niche use isn't bad. I actually like the unit, but that doesn't mean I get it all the time in any situation. If you feel like it's so amazing, power to you, but there's a reason it's getting buffed.