I agree with you that relic has become a big monotony in it's core but the answer is just this is it. I for one, loved the very first stage of the zenith weapon where i had to fight hard primals to get it meaning i had to grind them but i was improving my skills as well.
I believe the relic began its path in the atma stage where many people realised the goal behind it (and still there was no actual upgrade in the weapon) and even though you could do it in maybe 7-10 days with casual playing, there was an animus afterwards to ruin your motivation. I can't refer to the later stages as i did them only recently in the mega-nerfed mode for the glamour.
Overall i think of the relic as a an option for a weapon and nothing more. I chose not to do it at all at HW and if its the same at SB i still won't do it not because of the grind in all of its forms but because i simply don't have the time for it. Sorry but instead of farming 20k lores for the ??? stage i prefer waiting 7 weeks in my cozy couch for a shire weapon but this is just me.
I would certainly welcome a change in the relic system but as long as it does not satisfy me i would still refrain from doing it.