Vinny, the Borges comment was funny. I have wondered what a Mark Twain essay on Iñupiaq would look like.
I'm glad you mentioned Yupik, because I meant to say that those demonstratives I posted are Iñupiaq, though I think Yupik has similarities this way.
They're called suppletive paradigms, and it may be that Navajo has a lot more of them.
Well probably some of that. But probably also there were once some regular productive methods of generating them, but probably those productive constructions fell out of usage, and then passage of time corrupted them so that they no longer looked regular. That is plainly what happened with the Russian perfective/imperfective situation. And with lots of Spanish irregular verbs too. A few things like that, plus a lot more passage of time, etc, can generate lots of irregular forms for the dictionary, especially if you don't have countervailing simplification pressures.