I really liked leveling up through PvP in WoW (was not very effective but I liked it lol).
Although WoW had brackets so it didn't really sync you around, I'm not sure what it does now, but if they can make it so similar level players play with each other I'd like that. I'm concerned the sync up would just cause people not to enjoy PvP as much because they'd get tossed in with people who knew their job skills and it would be a guaranteed face roll lol. ("I'm still trying to read my tooltips" vs "1 2 3, 3 3, 4 5 6, alt 1, 2 1 3 4 2, get rekt").
Of course there are people who seem like they don't know anything about their job in PvP already, but I believe it would increase the amount of people who get in and then have a bad taste because it would be very likely you'd lose in a bad way in a position like that, especially if it's 1 team v 1 team content that's more balanced to skill (1 v 1 v 1 is quite a bit of luck sometimes, less skill based).
So yes I'd love to receive EXP from PvP, in a way that is feasible to level, but I'm not certain the PotD scale up is the best version of that. Part of that imo should be trying not to add too many different queue-able maps and just having one or two big roulette buttons tops (that also means changing achievements though, or have a really annoying achievement system). Might work better if they could cross data center the Duty Finder (don't want to make the queues too long).
Other thing I considered - to avoid destroying the PvP queue with too many brackets or having to do some fancy cross data center stuff, is perhaps they add some ways for people to purchase powerful rested like EXP bonuses. The mechanic basically you buy "250% bonus EXP, to 100K EXP" and you could use that to go out and level (could be a scroll, but I honestly prefer it to be a rested like system without a timer because I find the timer on the buff obnoxious). So you can do your PvP, get some awesome EXP buffs and then go level that other job - you do that first time leveling dungeon roulette with that buff on and its like a level and a half EXP now lol. Of course PotD as always ignores all things, so you can't use it in PotD. However, they could add an exp scroll on a buff timer in the next update if they wanted - since that is already do-able in game. Wolf mark EXP scroll for all jobs, that could be a respectable item.