First, you might not like it or want to do it, but that’s what it would take to acquire Hughes. He’s at worst the 3rd best D in the league, maybe the best. The cost to acquire that is going to be insane, 2 years left or not. If this trade went through, LA would instantly be a better team. Byfield was 2nd line calibre this year, Clarke 2nd pairing calibre at best, and Greentree isn’t on the team yet. The arguable best D in the game has a bigger impact than the three pieces LA would be giving up.
Second, “massively helping Vancouver’s rebuild/retool” would be them being able to keep Hughes. The only reason this is being talked about at all is because people think Hughes might want to leave.
Lastly, you are looking at that hypothetical Doughty proposal through the lense of hindsight. If LA were to have shopped Doughty at or near his peak, that’s the kind of packages they would have gotten, yes. But in this particular case, it doesn’t make sense because Doughty had started to decline already by the time VAN had drafted both Pettersson and Hughes.