You are right. It would only be usable by RetroFE for now, but other frontends could do the same to make the art sets work. You would need multple boxart images for multidisc games and you could still have individual cd art by using the full romname.
Example:
Sega CD - Roms
Slam City with Scottie Pippen (USA) (Disc 1).7z
Slam City with Scottie Pippen (USA) (Disc 2).7z
Slam City with Scottie Pippen (USA) (Disc 3).7z
Slam City with Scottie Pippen (USA) (Disc 4).7z
Boxart
Slam City with Scottie Pippen.png
Story
Slam City with Scottie Pippen.txt
Cart
Slam City with Scottie Pippen (USA) (Disc 1).png
Slam City with Scottie Pippen (USA) (Disc 2).png
Slam City with Scottie Pippen (USA) (Disc 3).png
Slam City with Scottie Pippen (USA) (Disc 4).png
In this example we can save 6 unneeded images and 3 videos if we want. I'm not saying that all the media "should" be like this, but rather it "could" be and RetroFE will still work.
I'm not sure how you strip tags Pieter but a simple Regex like this works
Regex.Replace(source, @"\s*?(?:\(.*?\)|\[.*?\]|\{.*?\})", "").Trim()