Adventures would be welcome too. Could even bump them into legendary and master now too. Literally anything to make patrol zones more interesting!

Don't know why they haven't vaulted Nessus or the EDZ yet. They don't really serve much of a purpose anymore apart from being the destinations for seasonal playlists. Maybe Devrim decides to retire and settles down in the City, and entrusts the Vanguard to look after the EDZ. Maybe a Pyramid arrives on Nessus and consumes it like the other planets, and we manage to extract Failsafe's hard drive and get her out of there safely (or she ends up MIA like Asher and Sloane). Just some ideas. Though it seems likely that one of them will be vaulted when Lightfall drops, since they're adding a new destination.

Doing their bounties is a cheap, easy way to earn some extra XP, and it'd also a good way to score some resources too. Not saying you need those things, but there are functions. Especially when the seasonal challenges make you go there.

If i recall flashpoints were essentially rerunning the story mission of a campaign. Now that bungie has campaigns with proper repeatability(minus beyond light) they are redundant.

Because they didn't really add anything interesting and were just an "easy Pinnacle" that people rushed to complete in 15 minutes. With content vaulting, it probably wasn't worthwhile to develop for new planets when the community barely engaged with it. They added Legend/Master Lost Sectors when the Flashpoints were removed, and those are probably more sustainable since Flashpoints had unique world bosses for each Public Event.