I don't believe requiring 1500 hours is the magic formula to a perfectly safe industry. As we all know, results will vary drastically based on the pilots natural skill, intellect, coordination, and experience. Having said that, I do believe the 1500 hour rule has and will continue to improve safety.
I realize the naysayers argue that it doesn't help to require 1500 hours because people can just tow banners and flight instruct their way to the airlines instead. I partially agree- We might really see some improvement if there were some kind of clause in there requiring certain type of operations (for example 500 hours flying charter operations in certain types of aircraft). However, with the current rule requiring 1500 hours we are at least forcing hours to gain experience. Some might get all those hours towing banners and flight instructing, alright fine. But others might instruct for a 6-12 months and then a charter job might be offered their way and they finish their hours doing that before heading to the regionals.
My point is even though it isn't the magic solution, I think the results of the 1500 rule are an improvement on safety if anything. Accident statistics speak for themselves. My only wish to improve it more would be to further require different types/operations to force the experience.