I think any new mode needs to play naturally with the games current loop and systems. I don't think that mode fits those criteria.
I would however like to see some of the poorly designed major conditions like hidden bunker and locked gate (maybe even arguably the boss raids) be turned into PvE modes with heavy, heavy Arc resistance. Largely because these modes don't work super well in PvEvP as it is currently set up and either result in a lot of losers, forces people to not engage with the mechanic, or exploit it to circumvent the concept.
They'd have to tweak the rewards compared to the average loss, but using those as exclusive places to get certain blue prints (as they currently are) is probably a sufficient reward. I don't think the game needs a PvE mode, you can get there pretty easily with some peaceful solo runs, but the current major map conditions that have some puzzle or boss component seem borderline dumb.