What I would like most is the option to challenge friends directly, or at least to make tables friends-only (the option already exists to limit spectators to friends, so adding the latter option does not seem too difficult). I find it tiresome to have to keep typing "Friends only, please," and kicking people, and I doubt that the other players enjoy being kicked.
It is, of course, possible that most of the community may actually think that even having this option is undesirable, as competitive, rated play would seem to mean that players should be willing to play anyone close enough to their own rating. My personal preference is for a friendly game and a pleasant chat, and not to care too much about ratings except possibly as an opportunity to learn from better players, but others almost certainly disagree. If the reason this option hasn't been implemented is that ShuffleIT doesn't actually consider it desirable, please let me know. I do very much appreciate their willingness to listen to user requests and suggestions.