Not a refusal, we just want to make sure we do it right and offer something that is appropriate and enticing without making people feel they have to do Group Ranked to get the reward they really want. It is a balancing act and we haven't found that perfect reward yet. If you have ideas for a Group specific reward (or any season rewards!) please post them in the Reward Suggestion thread, I check it every time there is a new post.
It's cool that you posted this at the start of the season, but why do you refuse to give unique rewards for group ranked?