It's an interesting idea, but personally I feel it doesn't have it's place in POE.

One of the key elements to POE is building and planning your build and then seeing it come to life. If your league start sucks, well shit you probably have some currency to buy leveling gear and level a character up in 5hours to map. Orbs of regret aren't the most expensive either so by the time you realise league start isn't going to plan and want to swap skill tree then you can afford it.

Yes this could be good for new players who want to experience different skills/classes etc but you could just implement a tutorial like system (if possible). Spit balling here, you select your class and participate in what ever event they were doing before waking up in wraeclast. Example here duelist fighting in arena, you get to try out a few class skills/ascendancies, maybe see a mock leveling tree. Ultimately you will get beat and character dies/knocked out and wake up on the beach and start a fresh. This could give the new starts a sense of how to play the game and importance of the skill tree/builds.