You Don't Actually Want a PvE Mode In this Game

You want a separate game built on the same bones!

This has been one of the more consistent requests since the game dropped and I totally agree that a story driven PvE experience in the modern flavor of Marathon would kick ass and I want to play that.

Bolting that awesome thing that you're imagining onto this game would not achieve the outcome you want. I spent a decade hearing Destiny players complaining about PvE vs PvP balance, development resource allocation, etc. and we have no reason to believe we wouldn't hit the same fundamental issues here.

Additionally, adding entirely new systems to a game reduces focus and increases bloat. One overwhelmingly positive consensus here is that the dev team is responding to feedback quickly and rolling out changes at a healthy cadence. As a game's scope and complexity increases, the ability for bungie to maintain that cadence decreases at an even larger rate.

There's a reason Overwatch 2 killed it's PvE mode. There's a reason Rainbow Six: Siege killed it's PvE mode. There's a reason only like 1 in 3 Call of Duty campaigns are decent. There's a reason Battlefield 6's campaign was bad. Slapping something fundamentally different from the core game on top of a game is hard, and not something that can be pivoted towards strictly due to user feedback. It's totally possible they've always planned to add some PvE content to this game, but adding PvE content to this game reactively is a huge risk.

The only, only, upsides to slapping it on top of this game are twofold: you already own this game, and you might get the thing you think you want faster. Completely valid reasons, but personally I'd rather have the good thing later than a mediocre thing sooner that jeopardizes the thing I'm enjoying now.