Many years ago, the T-Racks plugins were the staple of my setup, but I eventually became frustrated with IK's refusal to update them. My biggest gripe was the lack of a mix knob on their compressors, and even when they went from TR-4 to TR-5, they still didn't add mix knobs.
Eventually, they pretty much fell into disuse for me (just like Waves plugins). There are simply too many viable, affordable, and hassle-free alternatives available nowadadays.
I got MixBox at some ridiculously cheap discount, and while it's good, it's simply too late for me. I'm already set with all my mixing go-to's that I'll ever need.
And yeah, the installer and in-product merchandising is annoying and unprofessional. I think this is what's fueled most of the disdain that's been hurled in IK's direction.