Electrum plugin was made as a concept to be integrated with Electrum but Electrum programmers were afraid that mixer integration is bad for their reputation.
As it is - plugin is hard to install and ugly. But it works and has quite a few users.
Are there any plans for updating Electrum plugin and making it easier to use for newbies or maybe adding app for hardware wallets like Ledger or Trezor?
That would be amazing, even if not supported fully by manufacturers of hardware wallet devices.