Why is "New Account" grayed out in Electrum?
The Electrum (even 2.*) is BIP32 compatible for standard Electrum wallets. But BIP32 standard describes only one account. BIP44 extends it to multi-accounts.

If you use hardware wallet (for example Bitcoin Trezor) in Electrum, in this case the Electrum works as BIP44 compatible and you will be able to create other account.