Treasure Troves are most valuable the newer you are, or if you’ve deleted and restarted from scratch.
There is a (near?) guaranteed blueprint, a pretty high chance at a rare crafting mat esp. in elite+, and the normal loot from a high end chest to boot. I’ve even seen at least 2 purple items from them in addition to the blueprints.
That said if you are almost done with recipes they aren’t so great anymore… unless you need the purple crafting mats still. Definitely not worth actively seeking once you’ve finished with blueprints.