As one of the people that has completed this quest, The Vah is really just fine as it is now in terms of difficulty and time investment. Any of the more casual players can easily complete the hidden presences and get several really good clicky items in addition to the Vah tmap reward which is hard to replace for anybody until ~t8, despite being fairly easy to complete. Those who can and are willing to invest the time into collecting all the banners can raid Shar Vahl for some cool loots in addition to an amazing clicky.
The idea of * versions of mobs has been discussed before on these very forums and Thinkmeats himself, the guy that made the quest, shot them down for the same reason that you don't like them not existing; they're meant to be bottlenecks. I can only assume the reasons the Mielech the Reanimated has a * version is due to 2 factors, he's a cash mob which 65 groups keep down and because his step is still near the beginning of the quest before you have access to all of the side quests.
The fact of the matter here is that this quest is NOT required for progression in any way. The final reward is a really nice clicky, yes, but I've never said to myself "well damn, if I didn't have the Vah back there I couldn't beat this monster". It became like this for a little while when Marza had to balance content around people having 2 minute god mode, but now that the duration is only 30 seconds, it's not as easy as it once was to abuse.
Basically, this quest was meant to be long, time consuming, and difficult. If you don't want to put in the time that it takes to track raid mobs and assassination mobs, collect rare items, and get all of your banners, then don't do the quest.