Probably because libevdev isn't included in the RPi image. I've added it as a dependency to reicast and a 20170615 image is uploading try that
i just installed the Image 20170614 where i could not connect my ps3 controllers via bluetooth also. After updating to 20170615 i can connect them again. Since this version i cannot connect my bluetooth keyboard anymore. Is it possible that because of this libevdev? I can remember that i had the same problem with the retropie image. There you had to choice if you wanted to connect ps3 controllers via bluetooth or any other devices. Both at the same time was not possible.
My old "escelade" image i used before 20170615 allowed to connect my bluetooth keaboard and my ps3 controllers at the same time. That was pretty cool and your "retro gaming image" was the only one i found where both was working at the same time.
Do you have any clue what could have been different in the past image? If needed i can look after the specific escelade version i used before.