Um, it's abstract math, it's not going to help you build a flying car. Isn't proving a major conjecture enough?
Most of mathematics predates the modern American academic system. This immense body of work wasn't developed by people with a careful eye on the best way to get a good tenure-track job. It was developed by people who did math for one main reason: they were fascinated by math.
I am not a mathematician, but I haven't seen anyone suggest that Mochizuki's world is boring. It's difficult for me to imagine 19th-century mathematicians resisting the opportunity to become students again in a new, promising, and unfamiliar world.
The 21st-century reaction seems to be: I already got that degree, you want me to start over? WTF? Why? What's in it for me? How do I make a name for myself by studying someone else's theory, which might not even be true? And it's a pretty sensible reaction, given the institutions we have.