The biggest problem with 'mandatory' training beyond what is given to LEO's goes right back to the heart of this thread, MONEY.
Many agencies can't afford the weaponry, let alone extra, much needed training. I was at the range a few weeks back and some state officers were going trough some practice runs for their up-coming qualifications. My friend (range owner) is a state officer and firearms instructor and he was running the drills. They were having to use their own privately bought ammo so round count was critical for them. Some had no worries, but a couple were borderline and could have used a few hundred more rounds to boost their confidence for the qualification shoot.
Many LEO's are not 'gun folks' and only use them for 'the job'. Many have no interest in training beyond what they get on the job. My B-I-L is one of these types. He only shoots at the pre-qualification warm-up and to qualify. This is one area where mandatory training would be beneficial but cost prohibitive for most departments.
Private citizens are a whole different tater patch. It is very true that many who carry do so only because they can. However, requiring mandatory training as a condition of ownership or even to CCW would serve to open up a whole new can of bureaucratic red tape that we don't need.
Do LEO's need more training? Yes.
Do many citizens need more training? Yes.
Is making it mandatory the way to go? I say no (JMHO)..but I've been wrong before. 
I know what you mean I have a friend that is a LEO and I've helped him haul 10,000 rounds of frangible 5.56x45 and .40 s&w that him and two of his co-worker bought to attend a two-day training session.
I also have another friend that is a recruit for one of the local divisions and we were talking about guns and he told me about what he carries on duty. "I have a Glock 27, it's like the biggest one they make in .40." I tried to reason with him, but he was sure that that's what it was so I left it at that.
As far as the thing goes, it's true in so many aspects that it's just scary. If you look at most high ranking executives, especially the ones that work for the companies and banks that are asking for bailout money, they recieve a salary that could pay wages for 2000 or more average workers, and there is nothing that can be done about it. It just seems that it doesn't matter how hard you work to get where you are, but how much leverage you can hold on the person that writes the check.