They stopped adding epic quests because there is no need for them. When you ETR back to 20 you can post a group for legendary quests and let anyone from level 20 to 32 join. Legendary quests are great because everyone 20 or higher can play them.
That's fair but there isn't always a group to carry you through legendaries and without those a lot of builds basically can't do legendary R1 and man will struggle with Elite. I don't think it could hurt to have a bit more variety/pre-legendary XP available at that point for people doing the ETR grind, especially if you're doing multiple ETRs on a single heroic life which I have tended to do recently.
Personally I just wish there was a viable alternative to doing bloody Gianthold. I'd really like the next expansion's heroic content to 13-14 as we now have expansions for:
3-4 (along with lots of other viable high xp low level quests)
5-6 (again lots of other high XP quests around this level if you get sick of feywild)
7-8
10-12 (and at least 1 holy grail quest that can grind the entirety of 11-13 in an hour)
GIANTHOLD and lordsmarch plaza
multiple 15-17s (wheloon, sharn, even vale if you get extra stuck)
18-19
But nothing new for 13-14 for many years besides 4 quick but relatively low xp 14s.
I am so glad that I am basically finished with heroic TRs, but I've been doing some iconics and I skipped GH on my latest one and it made 15-20 a real slog.
So yeah, it'd be nice if some of the gaps got filled in both in heroic and epics. Surely it couldn't be that hard to scale a new pack here and there to add a mid-epics version or make epic versions of some old neglected quests that don't get legendary versions. But I guess any dev time that's not on priorities is wasted dev time so I can sympathise with there being no motion to do it.
But, it's at the point where if I'm trying to do an epic life quickly I get basically 0 reaper xp for 2/3 of the life because I will duck out on doing quests I really cba with and do slayers then try to find a decent legendary group for 28-30.