1. Restore different seed formats. Not only 12 words, but also 15, 18, 24.
2. It is possible to restore other popular seed formats. For example, Electrum seed format.
3. Allow the encrypted seed to be restored.
4. Recovery using a private key, using an encrypted private key.
5. Multi-signature wallet support.
6. Built-in DEX.
1. I haven't tried it, but i expect it should be possible since Wasabi explicitly state they support BIP 39. Source, https://docs.wasabiwallet.io/using-wasabi/BIPs.html.
2. I agree with @satscraper here. In addition, user should be encouraged to move their Bitcoin from Electrum to Wasabi by creating one or more transaction.
3. In case you refer to additional text or passphrase when you generate BIP 39, it's not encryption feature.
4. It's good idea, although i expect it'll supported in form of sweeping the coins (which associated with the private key) to address on opened wallet.
5. CoinJoin is big part of Wasabi, so personally i don't expect it'll be supported since you need to sign transaction many times quickly during CoinJoin process.
6. I also agree with @satscraper it's not really needed.