1) They tweaked it, added new items, appearances, etc. It was still a better experience than Nathria by some considerable distance, & was backed up by two solid single-boss raids as well. I didn't do Naxx in Vanilla, so it was totally new to me, & I was happy with it.
2) I played Ulduar at the time & got the Starcaller title during Wrath
Raid finder is fine, though - More eyes on something the better, & I'll never be the kind of person to hate on someone because they lack the ability to raid higher-tier content.
3) Multiple difficulty raiding so things like the above don't happen, Death Knights, Inscription, multi-spec...? Shadowlands leaves us with nothing that'll make it to the next expansion, apart from maybe a bit of influence from Torghast going forward.
4) They'd be better set planning on gameplay features that'd stand the test of time, rather than reinventing the wheel just to give the sheep a carrot on a stick to grind each & every patch/expansion. They added M+ just two expansions ago & that's a feature that WoW will carry through to the end of time, yet probably took no more development time than something like designing covenant abilities & conduits for each class, which will be gone in just a few months.
5) Well if we're comparing like that then I might as well throw in Wrath having more zones as a positive for it
After all, Icecrown is more relevant as a zone 13 years later than Torghast will be in 10.0.