(dammit, most of my post got lost because the thing had a hiccup)
No, you wanna see something unnecessary, see Book 1's love triangle right down to contradicting all that the franchise's thematically stood for just for the sake of conformity.
As part of what I said in the last post, it's not only thematically fitting for him to return (for both himself and Asami, especially as she's been unfairly written off as "bland/useless/just a love interest,") but it's practical in providing an improvised way to counter Kuvira and add a sense of depth/drama considering he's the only notable person that explicitly died fighting Kuvira.
The problems with Book 4 was that 1. It had too many sub-plots to properly deal with in the limited amount of time/eps and 2. Too much of it was spent on Mako babysitting Wu and ESPECIALLY Varrick, who was yet another character Bryke got too obsessed with and have only learned to dial it back in "Turf Wars."
I have, had and will continue to say it as long as it's relevant that Asami was criminally underused throughout the series and second only to Book 2, Book 4 really should've focused on her as a deuteragonist after Korra, regardless of Korrasami happening or not. She's spent the Time Skip rebuilding an entire city partly to restore the good name of the family business that was tainted by her father's terrorist activities, who's now trying to get back into her life after previously trying to kill her and she almost him (as the most pissed off we've ever seen her,) and doing/dealing with all this separate from her family of choice, namely her AWOL best friend that she took care of for two weeks and didn't hear back from after two years when it was only supposed to be mere weeks. Then factor in for the good of the same city she's been rebuilding years ago, she has to team with the very guy that nearly jacked her company and you have a wealth of narrative potential*,but somehow that was all reduced to a handful of scenes and mentions compared to a couple side characters sloooowly learn not to be insensitive dicks to everyone.
- With Korrasami in mind, combine all that and realizing she's bisexual and in love with said AWOL friend without telling anyone and you have a ready-made side-story/special (ex. Bardock's stories or Gohan's Garlic Junior Saga in DBZ) that (besides dancing around censorship,) could've rivaled "Korra Alone" in quality.