I don’t think I’d ever restart my island, because like others have said it would probably be too much to start from scratch, mostly collecting all the DIY’s again.
I would consider getting a new switch to get another island though seeing as mine is as old as a switch can get and is a little worn out. That way I get all the upsides of restarting without any of the downsides. Of course it’s the most expensive option but I think it’s worth it’s value in the long run. Having two islands would be neat.