What was the motivation behind Kane's first one-day title win against Austin?  Was it just to pop a big rating for the next night's re-match?  Was it to establish Kane as a true top guy (up to that point he seemed like the usual Undertaker monster-of-the-week who would fade away that year)?

He was supposed to be gone after Wrestlemania, in fact.  But he caught fire (ha!) and the rest is history.

But yeah, the title reign was just a deal to pop a rating because Kane was a guy who could both plausibly beat Austin due to the ridiculously biased stips, and then lose it back without getting damaged as a top guy.  Nothing more to it than that.