A lot of work is needed to get to the point where you get to upgrade from the CPL, let alone what is needed to get the CPL. And as Airbus38 says anyone can get a 2:2, 2:1 just by doing the minimum of work.
While it is perfectly true that the status of a degree is debased by some of the pathetic courses now on offer, with little or no academic rigour or intellectual demand, I see no logic in adding to that debasement by giving the ATPL degree equivalency. The ATPL exams require a large quantity of work memorising the answers to a specific, albeit changing, set of questions. Little depth of knowledge is required of the subjects covered - indeed, some subjects are deliberately simplified for the purposes of the course. Again, there is little intellectual demand or rigour in the course. It would be rather like saying that 14 GCSE's is equivalent to a degree simply because of the quantity of work required.
Quality is the hallmark of a worthwhile degree. The ATPL exams fail that criterion fairly spectacularly.
Scroggs