The US system came after some of the foreign, integrated college-med school systems and rejected those because they didn't give folks a broad education. More recently, (the 1970s), the notion of med school admissions was revamped out of a realization that this was a service industry, not a pure science, and that the kind of doctors patients wanted and the kind that are generated simply by taking nothing more than the prereq sciences did not jibe well. Since the late 70s you have seen an increase in non-sci majors, nontrads, minorities and women to the field. Like it or not, this is a service industry, one of the most important skills you are going to have is to be able to talk to people and find a connection with them. Having a more, not less, broad education helps you with this. Being more mature in years also can help with this. The notion that "I don't need physics, calculus, english" etc misses the point of a broad education. Our system gives you the opportunity to come out well rounded. It allows med schools to put together a diverse class of sci and non-sci individuals, folks with diverse experiences, not just folks who took some bio and chem and otherwise haven't expanded their horizons. The average age is 24 and climbing, not declining. And while maybe there are financial disincentives to spending so much time in school, the field demands it. Many of the shorter US allo paths are being phased out. Not because the folks aren't learning what they need, science-wise, but because there are so many advantages to accepting folks with the additional experiences a few extra years of seasoning and liberal arts education can bring, if you let it. As a premed you are champing at the bit anxious to start, I get that. But you are going to look back with nostalgia at your premed college life, if you do it right. It can be the most fundamental, most useful background you can get for a predominantly service industry. Spend the time taking things you won't use. Make yourself well rounded and able to converse on a multitude of non-sci subjects. Learn a foreign language. Maybe some business. And partake in the social offerings of college. It will shape you in ways far more important than simply taking the prereqs and rushing to med school. Once med school starts, you barely will have time for more than school. It's a limiting education -- you need to get your broad one first or you end up knowing nothing but biochem. And believe me, it's far easier to talk to patients if you've spent time outside of the classroom/lab/library during your 20s. US saw all the other educational models and picked this one, for good reason. The delay is intentional, and evolved from patient service needs, which frankly are as important as your desire to get through it quicker. Take advantage of this path, don't think of it as wasteful. It's not. It's important to your evolution to doctorhood. Speaking as a resident, I find I draw useful skills and knowledge from my college background and experience all the time in my patient care encounters, far more than from the basic science years of med school. To be a good doctor you often have to have experiences outside of the premed-med school path. I think there are actually still very good and beneficial reasons for a long undergrad.
And even to the extent that it gives some people exposure to other fields so they don't end up in med school for the wrong reasons would be a useful reason to maintain the liberal arts background. You have to realize that the US system was set up to decide who will be a doctor at the med school admissions level. We find it unfair to require folks to incur time and expense on this path only to get thrown out later, as they do in the UK and other countries. Here, you prove yourself in undergrad, are accepted, and once in med school in all probability you will become a doctor (less than 5% attrition). Foreign countries who accept folks right out of high school, before they have actually proved themselves, have much much higher attrition. They have to because they haven't allowed folks to mature and put together any sort of academic or EC resume. In the US 90% of the freshmen who go to college thinking they are "premed" will get pared away by the time they actually apply, and then 50% get in after that. so the folks who get in are destined for doctordom. it's a good system, doesn't force folks to incur high tuition debt only to get thrown out. It's a good system. We like it better, because those other systems existed before ours and we rejected using those. And further refined who gets in to med school in the 70s, once we realized what the profession was all about (service, not science) and once it was accepted that patients get a vote.