If 737s were single engine aeroplanes with less than 100 hours on the clock and 40% of an operator's fleet had suffered engine failures in the space of a week, I very much doubt they would be flying them!
I'm not disputing that they're a good aeroplane - whilst I haven't flown them many times, I actually think they're very good - but any attempt to diminish the significance of these events is seriously misguided. My argument is that if this is what happens when they are operated as per the operating handbook, clearly something is wrong.
It doesn't matter where the problem lies - whether it's a procedural change that needs to be made or a design change is irrelevant. The point is that if nothing is done, there's nothing preventing the same thing happening a third or fourth time, and whoever the poor bugger is that's flying it might not have any good options available to save the situation.