Totally agree. Timesinks and grinding are the name of the game with a design such as this. Grinding on grays is shit but as long as the grind is actually meaningful beyond the intended item, such as XP gain and/or the possibility of other loot upgrades while keying, then I'm perfectly fine with it.
I can't help but continue coming back to the epic quests. In EQ, every class had one and it was for a weapon (or in some cases, two weapons). Imagine those long, epic quests for not only weapons but for each individual visible armor slot too. Not exactly original I know but could definitely be designed around mostly group content with some solo and raid mixed in as well. Now we're talking about 8-10 slots each with its own epic quest line requiring the player to complete content all over the game world. That sounds to me like it would be fairly time-intensive for 99% of the player pop.
Of course, epics still bring numerous challenges to the game as well, with balance being at the top. Additionally, that many quest lines across every class would require a metric fuckton of dev time to design and, if history repeated itself, would typically have a much shorter shelf life than intended, especially once expansions roll out. Not to mention the elitist bullshit that comes with them ("Hey, we need a tank for orc_camp_2. What's that? You don't have your epics yet? Sorry, you can't join the group").