The bigger question could be, why, in 1988, did the Republican party voters pick Bush 41 in the primaries???
Yes, Bush was in position to run for president because of being Reagan’s VP, but it’s not like it was an automatic process. Bush 41 was running in the primaries against a number of others, and he won that process. Why did GOP voters then pick Bush to succeed Reagan?????
Michael Dukakis was the democrat pick. It was either Bush or Dukakis. My guess, GOP voters picked Bush because of loyalty factors, not because he was the best candidate. Just like they selected Hillary, because it "was her turn". Again, politics. Not the most logical or best picks, that sucks but that's the way it is.