Interesting question, one I've given thought to as well. It seems that AVR manufactures save their backlit remotes for their flagship receivers. I've owned a several receivers in my days and the only ones that ever had backlight were the top of the line receivers. My current receiver is a Marantz sr8012 and it is backlit, but like Peter said, third party remotes are the way to go if you have multiple devices to control, which, if you have an AVR, you obviously have multiple devices connected to it to control. Logitech/Harmony is probably the most popular and most of their remotes are backlit and/or have LCD display-touchscreens.
Den: Sony XBR75x950g, Marantz sr8012, ATV4k, Oppo bdp105, Emotiva XPR-5/UPA-2, NHT ClassicThree+C3C/iC4x4, Hsu,7.2.4
Bedroom: Samsung 64f8500, Denon 4311, ATVHD, Oppo bdp93, NHT Absolute Towers x2, Classic2Center, Classic2 Surround, M&K sub 5.1
Headbanging: MacMini/Roon/Tidal HA-1, ProJect PreBox s2 PM-1, Senheisser 6xx