This is a problem of the "rush to the last tier" mentality (and I have already pointed out several times) (which is also part of the problem with light/micro light vehicles) but I doubt the mod team want to change that.
No, it's not a matter of mentality, that mentality will exist in any game design. People want to get to the last stage of their construction as early as possible. It's just normal gameloop pattern. The problem is not what you describe, it is exactly what Esxile wrote, the Brumm is too easily accessible and comes ages before any proper hard counter.
It's the only unit in T4 that feels like a tiny premium doctrine style speciality unit that vaporises too much, too easily. I love it, i love playing and microing around with it, but it feels too much, too easily accessible, and even covers my need for Pwerfers. I feel it should not overpower soft (even hard) counters too much. I can roll up to AT Guns with it, wipe it, and roll back too easily. Infantry with AT? Gone! Perhaps some armour reduction or speed reduction is needed. Some drawback. It even soft counters AT. Or somehow make the manual mode less potent. The more I use it, the better I get with it. And I'm only discovering its strengths, we've seen how potent it can get in recent disputed videos.