Premium availability changes the equation on upgrades.

I live in base and drive to work. I don’t work holidays, or weekends unless premium. My line awards are in my top 20 choices at worst - usually within top 10. I get my vacation choices.

That’s an awful lot to give away when you can make up the money difference with premium. On the other hand, take away the premium, and upgrade to junior reserve captain becomes a little more attractive.

There is a reason why at most airlines, commuting to a high cost of living area and sitting reserves tends to yield the heavy bypass numbers.