I'll live with whatever choice anyone makes on the topic. The zones are unused and it pretty much doesn't matter if they open them up. Of course, if something is done to equalize the experience gained in planes zones, my opinion might change.
Even if the zones are opened, some might check them out for curiosity's sake, realize that they are getting sorry experience, and jump right back to one of the newer expansions.
I loved the experiences I gained from doing PoP raids. I did them all as an open raid participant, so it took me forever. If the game were as fun today as it was in those times, I might be playing more than a couple of hours a week.