Because it's still a huge screen with high quality audio?
Why would you care how the image gets on the screen of it ends up looking better?
On the contrary, the audio is horrible (Yes, I've heard it). Movie screens are perforated to permit "screen speakers" to be positioned directly behind the screen. LED screens do not allow such positioning. The center channel (i.e. where most dialog emanates) is positioned above the top of the screen. This has the effect of disassociating the voice from the speaker and breaking the suspension of disbelief.
I doubt this will break the suspension of disbelief that easily. People have no problem listening to Movies on crappy stereo or mono on their laptop's display speakers or using crappy 3.5mm earplugs (sometimes with only one plug in the ears).
This is different to “LED TVs” at home. It’s closer to an OLED TV since each pixel in this cinema screen is individually lit.
Because of its size and because of the sound system, and also because movies are released to cinemas earlier than you can watch them at home?
This comment implies that the conventional cinema screen setup is more preferable over a TV screen when it comes to watching movies, and I have to agree. Maybe not for other content, but staring against any more powerful illuminating surface in a dark room for 2 hours would strain the eyes too much to be pleasurable.