There’s only one problem with your alternative history: Bush wanted Roberts as CJ all along. Had Roberts been confirmed as an AJ prior to Rehnquist’s death, Bush still would have nominated Roberts for CJ.
As for why residents don’t nominate state supreme court justices to SCOTUS, one of the main reasons is that few prominent state supreme court justices are as young as prominent judges in the federal judiciary that end up in SCOTUS shortlists. That’s one of the problems with lifetime appointments for SCOTUS; presidents rarely name anyone 60 or older because the you ger the nominee the longer he’ll be on the Court. Personally, I support the constitutional amendment that has been discussed for several years (and that Rick Perry recently touted) to make SCOTUS tems last 18 years (with a vacancy every two years), which would eliminate the disincentive to nominating a 65-year-old to SCOTUS.
Interestingly enough, Ted Cruz agrees with me that voters ought to be allowed to vote out activist SCOTUS judges. Having them up for retention every decade or so would be a heck of a lot easier than trying to impeach some rogue federal judge.
Of course I don’t think it would solve the gay marriage insanity, thanks to the citizens of this nation going off the deep end and the left framing butt sex as a “civil rights” issue. And of course, it would also give leftists the opporunity to vote out conservative judges like Scalia.
Still, its got to be better than the current status quo where they’re given lifetime jobs no matter what. With Ted Cruz throwing his weight behind this, maybe the “Democracy, not a Republic” morons will wake up and realize we need MORE democracy in america, not less. If not, I enjoy seeing their beloved state legislatures putting the screws to them and ignoring public opinion on the Confederate flag. You can’t fit stupid.