I would love to see the group limit go up, but I agree with others have stated in previous post, groups should be fixed first. I assume LL wouldn't up the limit until they are are the server could handle it.
P.S I've noticed more designers are using a system that allows you to subscribe for updates. You get them inworld and via email, instead of joining a group. So, maybe that will become more and more popular and will give shoppers less of a need to join groups for shopping and more space for whatever else they might need it for.