It is really interesting, I have the "Argh no" knee jerk reaction. But in fact, I have to admit the usability argument makes complete sense, and can not be beaten by subjective or tradition arguments.
(I feel it is the same sterile debate between automatic vs manual cars. I have argued for hours that it makes absolutely no sense to have a manual car and be forced to use two feet and one hand, when you can drive the same way using only one foot, and occasionally one hand.)
In the end it is easier to use, point. I'll have to order a 4 colours deck and give it a serious try.
One could go further, and question the use of suits. It clearly stems from tradition, older card game, etc. But
if the end goal is only to have 4 distincts symbols,
perhaps the traditional shapes could be improved and replaced by something even more immediately identifiable? With 4 super distincts colours that even colourblind people could differentiate?