I am doing Stella Radians right now and enjoy it. But the 7 million Karma you gotta farm is a bit overkill in my opinion. I know the best karma farms out there, so I am not looking for advice on this (unless there is a sleeper nobody knows about?).
I don't complain about a Legendary taking long/needing loads of resources - It's kinda the idea; a long term QOL / Cosmetic goal you don't "need" but want and guides you through different content and lets you "accidentally" progress your Account in completely different content too. That's one of the main reasons I like the concept of Legendaries - no hurry, since it's stats and such aren't better, but it's still chase-worthy due to many different aspects.
BUT 7 million Karma is gonna be the bottleneck. I will have easily completed all other steps and will need to put in the same amount of hours again just for the Karma farm, which isn't necessarily fun if focused on specifically.
I am at 1,5m right now and, if I were to guess, I probably have accumulated around 10 million Karma total which I've spent on other Leggies and Achievements. I never rlly focused on karma farming, sure, but I have a couple hundred hours of playtime and if those will give me just around 1.5 times the Karma I need for one leggy, it's a bit out of proportion.
If I farm Karma with the best methods out there (excluding winter's day) I would have to farm nearly 40h straight for 7 million karma, and even with wintersday it will be around 30h. If those 30-40h would just be "regular playtime" I wouldn't say anything, that would actually not be that much, but it's dedicated, numbing karma farming.
Do most Players "just have" millions of karma laying around and ANet wanted a sink? Or how did this sudden increase from around 2 million Karma for a leggy up to 7m happen?
Not discouraged, not raging or ranting, just a little "oof"-feeling. :)
EDIT: Got a couple insights and came to the conclusion that, yes, 7m karma is a lot to farm, but it's also gathered from all content, so with the not super high frequency of karma sink releases, it's easy to just "have" it at your disposal and it's not forcing you to do a specific content. It just happens to be a currency where players have lots of different "starting points", therefore hard to balance "correctly".
TL;DR: 7 million karma is probably too much when starting at 0 and will take too much time compared to the other steps within the legendary, but since you get it from all sources it can be expected for players to just "have it at their disposal" and it's not forcing you to do a specific content either.