I'm tired of hearing about new players getting upset and/or quitting game after bad experiences in ARR content. This is a really good game but we're losing people all the time before they reach the best stuff. I think it should be quite a high priority to adjust the early game experience, at least piece by piece in patches so it doesn't divert much resources away from new content.

CM & Prae in particular should have been altered long ago... at a mininum just place a warning when they are unlocked and added to duty finder which says many cutscenes will play during this duty and it's recommended to form a party with likeminded players who have time to watch. A better but more resource-intensive solution would be completely reworking and rebalancing those instances, and add new rewards like glamor/minions to them to justify the rework so existing players can get some value out of them.

As for the pre-HW msq quest slog, just change as many filler quests into sidequests as possible to make them optional. One more option is to make an expansion that is largely about revisiting ARR zones and roll all the reworking old stuff into that xpac alongside improving the zones. Add flight and swim, extended sections bolted onto the old maps which are only accessible by flight or new msq, with high-level enemies suitable for the new level cap.