I wasn't aware that you can lose you class (if that's what's happening). I have a lot of D-Miles btw.
But the thing is Simplified Ryoko was the basic set that you start with and in that page it says it is available for the regular member(no class).
If it's been over a year since you last properly used the site, what's probably happened is that your user class dropped.
By earning enough D-Miles in the current year (or a different amount in the previous year) you qualify for increased user classes that entitle you to additional site features, including the access to the piece styles you've mentioned.
I can't comment on how receptive 81Dojo would be to further piece graphic suggestions, but I do know that there's a set made by user CouchTomato that are used on pychess-variants called "1-kanji guided" that preserve kanji, but distinguish pieces by colour, and indicate their movements via subtle patterns in the coloured backgrounds.