TRing is boring because all they do is repeat those same 30 quests over and over, week after week.
TRing for most people is just replaying the entire game. I go slow enough that (so far) it's never gotten boring. I just replayed through Max Payne 3 again a few weeks ago. It had been 4 months or so since the first time I played it, and it was very enjoyable again the second time through. If I played it all the way through 20 times in 20 weeks, I'm guessing it would start to get boring. Especially I only played the 2nd level 10 times during each play-through instead of all 10 levels.
TRing through all 300 quests, over a couple of months with my TWF melee, and then doing it again with wizard, and then my monk archer, and then my fvs, and then my bard/rogue, and then my barbarian, keeps the game very fresh. By the time I'm back to the TWF melee again it's been a year since I played through game with that guy. So I AM replaying the entire game. Not grinding anything.
Much more enjoyable for me than grinding out the 1 quest that drops that 1 named item I want at end-game.
However, I fully support more end-game raids with great named loot for powergamers (and me) to grind for. I don't mind "grinding" raids because of the 20th list. Plus I usually play them every 3 days so it's not much of a grind. It's a nice change of pace from my current TR project.