And as somebody who wrote NeXT software for a number of years, they never really aimed to solve anybody's problem particularly well.
If I had to sum up the NeXT, I'd call it "a much better Mac". Which isn't surprising given that Jobs started right after getting forced out of Apple, and took a number of Mac folks with him. But as you say, $6,500 was way too much for the Mac's strongest market, education; that's like $13k in 2020 dollars.
Instead it was priced like a workstation, but it also wasn't great for that, in that it was a totally new OS and didn't have much software available out of the gate. I've heard of multiple schools that ended up with NeXT labs where almost nobody used them.
The only niche where I really saw adoption was with financial traders, who had money to burn and liked the rapid development speed you could get compared with other platforms of the day. But that was never a goal, just a happy accident.
So in retrospect, I feel the whole thing was not about helping any specific customer, but about Steve Jobs and his feelings about getting booted from Apple.