I'm not disagreeing with you. I think requiring 1500 hours is a good thing. I used to not think so, but now I realize experience definitely helps. I just have a hard time believing 1,000 hours towing banners rather than 1,000 hours in a Q400 would have prevented the CA from stalling the airplane. I currently fly a Beechjet 400 and I've learned more in the last 100 hours than I did in the 700 hours before that. Not just because its a new airplane, but because its more complex, I'm flying into busier airports with a higher workload, and things just generally happen a lot faster. I have to be on my toes.
Yes, you do learn a lot in those first 100 hours in a new turbine powered aircraft. But what you are missing is that you may not have the same readiness (laws of learning) too learn what you should learn in those 100 hours if you don't have the fundamentals down in the previous 500 hours instructing, banner towing, etc. Just the opportunity to scare yourself a couple of times on those 500 hours are learning experiences you carry with you forever!
This is what people don't get. Yes, most any 250 hour commercial pilot can be trained to manipulate the controls of most any turbine powered aircraft in a reasonable amount of time. But it's the intangibles that you don't learn because of the lack of experience that is the true cause if many accidents. It's very rarely airmanship that is a contributing factor in an accident. It's more likely that it's aeronautical decision making and human factors that perpetuated the chain of events that led to an accident. Those 1000 hours are supposed to be for learning everything else other than the physical art of flying.