Is TBC really more niche than HC?

I don't understand it because I am all about keeping your progress and loved the idea of era, I am not sure I even want to try HC. But I assume HC servers are going to be permanent. I enjoyed TBC alot, but its problems did bother me, so now I can only hope for a next one managed better. Flying mounts were not what killed pvp, it got focused more in certain areas of small Outland and I think phase 2 was really when servers went one-sided because griefing at TK graveyard and SCC cave were too much for many guilds. Wotlk style summoning inside instances can help this. The NPCs for the spirit towers in terrokar can be made unkillable. I am not sure about the idea of raid-wide bloodlust, and I am very against TBC dualspec, but if these are also changes necessary to make TBC lovable for everyone, I won't be against them.