I had to look at the request twice, at first I thought you were asking about black A4, however there are many A4 black models that offer the 60ppm speed.
I'm on the fence with a color offering for A4. Never pushed it because I didn't have it in A4, never had a client ask me for that speed in color when they were not producing 11x17 or 12x18 or producing full color booklets.
I believe that all A4 devices need more robust finishing options, in fact I'll go as far as A4s need to have all of the options of A3 devices. Booklet Finisher, punch, internal and external finishers, and folding option.
In most cases most of the copier manufacturers A4 models have a higher cost per page than their A3 counterparts. In order to have them take more market share away from A3, the A4s must have the cost per page model of A3 with color or black. Hope this helps