Simon Cowell -- Zayn Who??? One Direction's Better Than Ever

Maybe Zayn Malik should've left One Direction long ago ... is what you might think after hearing the group's producer Simon Cowell gush about the new foursome.

Simon's been mum about Zayn's departure, but finally spoke out Thursday night on "The Late Late Show with James Corden" -- and revealed how he reacted when he first got the news. Think hara-kiri.

More importantly to 1Ders everywhere ... Cowell leaked a few details about the upcoming album -- and applauds Harry Styles and the other 3 (sorry, guys) ... for not missing a beat right after Zayn bailed.

Watch and listen closely to Simon -- he's either putting the best spin possible on a bad sitch, or the group really is better now.