You can. Just enter any segwit address on the withdrawal page.
No. You are forced to use a legacy address as your profile address which also acts as your default withdrawal address which is only used if you don't enter another address when you withdraw or you use auto withdraw. The reason you can't use a Bech32 address in your profile is that our database was created many years before they existed. It would require a major database reorganisation resulting in many hours or even days of the site being unavailable to update that. We decided that wasn't worth it for the minor inconvenience of not being able to set a Bech32 address in the profile.