Creating a new character will allow you to see the additional hair/beards they added recently. Other than that, the only reason to use a new character would be to preserve your stats on your old one or to make it a bit more of a challenge at the start.

World wise, it would be more beneficial to start a new one. The world gen changed a bit for mistlands between older maps and now.
Old gens will have mistlands be mostly small islands, where the new ones will be larger.
The elevation of the old worlds is also more drastic making it harder to explore imo.