As the Cycles main focus is percussion I think it’s fine that it doesn’t have an attack envelope, and the LFO trick works - paired with the kinda crazy controls and parameter locks you can get a lot of movement with that setup anyway.
But I do see the desire of it, however the limited parameter set is what gets in the way - many have asked for Func + Decay for attack, but how would you then parameter lock it? And it would be missing from the panel - it’s a lot to consider in the end. (Also the design principles of the Model:Series goes against secondary functions for the most part)