Just like y1, the Solstice Armor is going to be obsolete again when y3 rolls around. What's the point of farming and grinding to obtain and upgrade the Solstice armor if it won't be worth using when Shadowkeep drops a month later?
This is exactly what happened between Solstice y1 and Forsaken, hell this is the same thing that's been happening with almost every yearly update (except TTK to RoI).
I get that Bungie wants to promote people playing the new content, but it's new content. People are going to play it because there's new stories, quests, loot, etc. You don't need to make us feel like we've been grinding for nothing.
I don't see much point in working my ass off to get the Solstice armor when it's going to be dismantled a month later.