What are other software products / companies with horrible design but get the job done?
Consumer products are like Chipotle: streamlined menu, built for efficiency and elegance. Enterprise products are like the Cheesecake Factory: you want a steak, pasta, pancakes, and a margarita? Go for it! Why is there a full f*ing bar in the back? Who knows!
It's hard to have great design when you have to do so much.
That isn't true for all though, many AWS services seem like they are 'console first' and do wonky shit in the console that is hard to do using APIs. Those services are incredibly frustrating.
Most AWS teams own their own console from what I've read here. And the smaller orgs often don't have any designers - backend engineers build the first iterations of the console.
I agree with your point - If a product solves a real problem, design/usability is a secondary concern. This is particularly dependent on the space, in my experience. In my fintech world, a bank will give you a massive amount of $$$ for a dead-simple form + button if it eliminates a workflow problem. They really could care less if it looks like it's from the 90s (most of their stuff looks that way, anyway).