I don't see any good reason why a veteran player would want to go back in there to actually help these new players aside from a good Sherpa heart.
I see and agree with this viewpoint. At the end of the day, not every single activity in the game can cast the widest net to be the most important, up to date activity available to every single type of player. Things will naturally fall to the side as new things come online, as changes are made to sandbox, or a ton of other reasons.
Having the top preforming weapon, perfectly crafted to a T isn't always a top priority for a player. It can be difficult to pull oneself out of their given player type, but hear me out. Many of us here on this reddit fall into that "Top 5%" type of engaged player. Many of us have been on day 1 grinding out our most desired rolls to have the perfect builds for a given endgame activity.
For others who aren't necessarily here, they're just starting to ramp up. They're getting their first (or second) Garden runs done, freshly discovering some fun rolls on the Auto rifle while trying to do an encounter challenge that they just learned about. Some may still be going for a given seal/title. Some might simply want to earn all of the armor from the older raids for their Guardian appearance. The changes might get them more involved with raiding communities or groups, fueling future desires to take on those day 1 raids or endgame pieces of content. Sure, the weapons they get might not be the best as they discover new ones, but maybe they'll find one that "fits" in the Crucible as they start to partake in PvP. Or maybe they'll find a fun weapon to use in Nightfalls while they continue to hunt craftable weapon frames that they didn't even know existed.
We feel this feature can be the start of something exciting and fun without requiring major lift from too many teams, leaving room for great feedback from players and potential for future growth, if that makes sense...
As an example (well, a few things touched on here) - your question as to why we didn't update some of these for weapon crafting. This would require a bit of time from the team to spin up additional craftable weapons on top of what's being planned for future seasons. We'd need to get some investment folks spun up on making sure those drop rates were working well for red boarders. If we wanted to change out perks, weapons folks would need to deprioritize other in-flight work items for tuning or new stuff to refresh these pools. Test time increases. Loc time increases as we make more copies of weapons that need translated strings. Lots of other things could be impacted if things go sideways. With this initial offering, we hit a few high-priority feedback items specific to "As a player, I'd love to jump back in to some old raids." A pinnacle, some powerfuls, some guns&armor you may not have, and some potential help towards exotic quests (or drops) can be great for a massive population that hasn't engaged deeply in raids.
I don't want to come off as saying 'these will never happen', but this first step in getting Raid and Dungeon rotators online is, well, to get some folks engaged in it and have the feature available after a few years of requests. In the live game environment that is Destiny, we can improve over time. New perks? Maybe. Crafting? Who knows. We'll be grabbing your feedback and passing it up to appropriate parties.
Apologies if my little ramble here is rough on the eyes, but hope it gives some context.