Yes, please -- this would enable new features in lots of Roku apps and make the platform much more attractive. I use Emby and this is a major inconvenience, and a reason I am considering competing boxes.
I was in the same boat as you and ended up using Fire TV devices with Emby. Fire TV devices support MKV files with embedded PGS subtitles. Emby has the option to prevent playback that requires transcoding. This has been a great combo.
I prefer Roku devices but the lack of image based subtitle support is a deal breaker for me.
