That is part of the issue. Of course, like all systems, PvP changes expansions to expansion. There are certainly better systems than what we have now. Many consider the Cata-MoP the best PvP times all around with balance, gearing, WPvP, and rated play. WoD also gave us some easier systems for gearing like Ashran. There is a whole thread on PvP gearing and accessibility here on the Community Council, so I won’t belabor the point. To give a short answer, yes, PvP gearing is a huge barrier for players getting out in the world, trying less choreographed RP-PvP events, and staying engaged in the game as a whole.
Im an altaholic. I have a 60, a 50, and various other lower alts on WrA. Real life and Shadowlands is really getting in the way of me being around more.
I like this, and I think flying should stay overall. But in areas where people congregate, that should feel full, they should be visibly full with players. All faction cities were designed without flying in mind and while I’ve certainly had my fun abusing and using Stormwind rooftops or outer walls, I don’t think thats the accessibility to unreachable spots you’re thinking of.
There is of course the need for major redesign in some places, Thunder Bluff and Exodar come to mind first. I don’t think a mild restriction for flying to city limits would really effect the accessibility to the rest of the world.
I would be an… Emerald Dream 
Pls don’t kill me again in AB 