How important is an LCD screen on your streamer?

Screens emit EMI, which is largely your digital source's worst enemy. Keep them off as much as you can to lower the noise floor and hear your system perform at its best rather than seeing what is playing.

And I don't know what you're talking about with regards to Aurender. They have some of the biggest, clearest screens on the market on all of their products. That said, as others mention, they have options to turn them off, and most people do this because of the reason I state above.

Yes, Aurrender has a switch that makes the screen turn off whenever the music is playing. Great feature… vs just always off. 

The screen isn’t particularly important to me when streaming because I use Roon.

An iPad serves as a control point and a TV on the wall between the loudspeakers displays what’s playing and a picture of the artist.

It’s a very nice feature.