Yes but how would that say anything specifically about a particular topic unless it was a defining and undeniable circumstance that happened during the presidency like a war or major scandal - and even then I think it's hard to confidently say "this is why people voted for X" without proper polling (and even that we know how accurate it is - but at least it'd be data).

Because the single largest thing people vote for is how much better they're doing now than 4 years ago. That's just been true forever.