I would much rather see Cruz not repeat Reagan’s mistake as both members of the Bush family set the GOP back. If an establishment candidate has to be picked I personally would much rather have Walker than Rubio. Jmo.
I’m not so sure it was a mistake - yes, it gave us one term of GHWB and two of GWB. However, Reagan had to make sure he’d win - and while it was an electoral landslide, he only got just over 50% of the vote. Both Carter and 3rd party GOPe Anderson may have fared better if he had not. Reagan may have won regardless, but definitely by a lower margin - so I think he was smart to play it safe.
I agree that I’d also prefer Walker over Rubio, and also wouldn’t mind Walker in the top spot. But since it’s unlikely that VP’s will actually wield any power, then I think choosing one to simply help you win makes sense.