Legendaries in Legion are drastically different than just getting BiS from a raid. Getting BiS gear that's the same item level as what you already have is at most a 1-5% DPS boost in all but the rarest occasions (such as the Gavel of the First Arbiter from SL, which was a significant boost over other weapons even higher ilvl than it). Legion Legendaries, on the other hand, the difference between the best and worst legendary could constitute for some classes as much as a 20% DPS boost. For most it was 15%. Even the classes with the most balanced legendaries saw greater than 5% DPS boost by getting their best from their worst legendary.
Wakening Essence wasn't added to the game until patch 7.3.2, the patch shortly before the final raid tier opened. You are comparing a system that was flawed throughout the first 1 year and 8 months of an expansion before it finally got fixed to the first week of a brand new expansion and using it as some scapegoat to explain why Dragonflight is worse in your mind. 614 days to fix a problem people brought up as a concern from day 1. Your rose-tinted goggles are blinding you to just how bad some of the systems in Legion were for a large portion of the expansion. This is why it's relevant. You're comparing an end-of-expansion feature to week one features when not everything is even unlocked yet. You're judging the first week of Dragonflight by comparing it to Legion as it was during it's final patch cycles. The entire point of this entire thread is about the perceived lack of content at max level during the first week. Do you even remember what week one Legion was like? Considering you seem so hyper-focused on Wakening Essence, a feature that wasn't even added until the end of the expansion, I doubt it. Week one of Legion had, at max level, even fewer features than Shadowlands or Dragonflight coupled with the issues of Legendaries. That is a far more fair comparison for the topic at hand.