Because all those things you mention are only super triple awesome "good deals" consistently and to the large colloquial extent implied for a very tiny fraction of the pilot group. The few junior upgrades that happen because of senior pilots camping in the right seat for those super awesome good deals aren't anywhere near enough to offset improved pay and QOL for the vast majority of the group.

I'm 100% in favor of working the system as able. I just think the perception that a sizeable majority support the very very few who can capitalize on the magic even at the expense of across the board improvements is highly overstated. That said, I'd wager that this contract won't significantly attempt to alter the deals of the few. Next time when the cycles of the industry swing the other way though, they will likely be gone with extreme prejudice.