Let me be a devil’s advocate in this one :)
The whole point of portals in expansion’s hubs is accumulating players in the current place, to feel more engaged with a continent. If you feel obliged to bind your hearthstone to one of the Pandaria shrines after Pandaria like it was in Draenor, it is wrong. The only thing that’s still not holding you in Eternal Blossoms was the Dalaran’s overlap in Legion.
Why would a player return to an expansion long overdue, invoking a shower of its memories every single time you need a travel? It’s living in the past, no more, no less.
Legion went over the top, adding portals to some insane amount of places. This was done due to class order/artifact questlines, which were literally scattered all over Azeroth. And even so they required travel: for example, Karazhan portal served as a path to Karazhan itself, but also Duskwood, Blasted Lands and Pirate Bay where some events occurred. It was meant to equalize the storyline playthrough time between classes and specs, but it went out of control: players took that as granted.
Well, it is not. The ideal cycle should be this:
1. Providing the convenient portal access paths vital to the current expansion (like Silithus in BfA, albeit we have an Uldum path 2 minutes away).
2. Removing all the portals except to the faction capital from central expansion hub after a player engages into the further leveling content.
That is what Blizzard is trying to do. True, if they kept doing this after Pandaria, every next expansion (Shrines -> Ashran -> Dalaran), we would have already got used to the cycle and taken that as granted. It’s no evil plan or conspiracy – it’s correcting their mistakes. Surely when player is planning to clear Dragon Soul, 2 minutes per week added to 30-40 minutes of cleaning time is not a tragedy?
Essentially it’s not such a scary change. Even the most controversial portal – Caverns – is not really an issue – yes, there is an Uldum portal with a flight path straight to its entrance, and trust me, it’s not the worst.
My pre-Legion Karazhan trips for the Attumen’s horse took my toons to Stormwind, then to Duskwood on Alliance side, and Ogrimmar -> Grom’gol by zeppelin -> Karazhan on the Horde toons. A travel path to either Black Temple or Ashes of Al’ar was a teleport to Hellfire Peninsula and a 5-minute direct flight across Twisting Nether, or wasting up to 7-10 minutes with flight taxi across 4 zones. This looks much worse, isn’t it? And I did it on 10 toons weekly until both dropped.
Personally I do not miss the portals that much: in fact, I completely forgot about Karazhan portal and traveled Ogri -> Gromgol -> Stormwind during Saurfang questline. Although I main and always mained a mage, logging in on another class doesn’t feel ripped off means to travel.
Also think about it lorewise: every next portal rips the fabric of reality, so ripping AND sustaining the dozens of them in more and more places is frankly quite disturbing.
My keypoint is: the portal network must not be the reason to cling to older expansions.