How to make the game better for new players?

[Seraphor]

Thats not really a problem. one of the biggest complaints about the MSQ is that much of it shouldnt be in the MSQ and should be side quests already. this has been true with every expansion and you can guarantee it'll be the same in 6.0 as well

You wouldnt have to make the MSQ longer becaue of it at all.. The only reason the msq is as big as it is in an expansion is because it aims to grant enough exp to get you to the level cap..

making sections of it optional. would allow players that want the EXP to go and do the optional parts.. but players who don't or have already levelled ahead of the story could just say No thanks Alphinaud catch ya later.. and cut the filler out. and resume the story where it goes back to the main plot..

Those quests are there for a reason. So that you don't complete the MSQ for an entire expansion in just a couple of hours.
They will add in enough fetch quests to pad out the MSQ to the length they want it to be, and to maintain pacing. They don't want you rushing through each new open world zone in 30 minutes, they want you to fight enough things in there, and talk to enough NPCs, to make it feel like you've used what they've given you.
Again any 'optional' questing in any capacity is literally just side quests.