While I agree that a good pilot in a BJ, TP or even big recip can be trained to fly a big jet internationally, the question becomes one of how much training. The airlines in question, (whether rightly or wrongly) have established arbitrary weight and equipment requirements in order to put a limit on required training. I can tell you that they haven't been very scientific in how they've gone about it but in fact, there is a vague correlation between size of the equipment and the amount of training required.
In EK's case, they hired a bunch of RJ guys a few years ago but failed to do a rigorous analysis of what training would be required of guys coming from small jets flying in a strictly domestic environment to flying a very large jet internationally. In fact, they decided to reduce the amount of training at the same time. It should be no big surprize that some had problems. As a result, a bias developed about RJ pilots and the size of their aircraft. In fact, if someone is a competent pilot, they can fly anything with the proper training.
I think that you will find that it is human nature to cast blame elsewhere when the real fault might lie closer to home. This is not unique to EK or this part of the world though it does seem to be institutionalized here. EK will relax the requirements when they perceive the market requires it. Whether they learn from their past mistake is another question entirely.