The main problem with their market visa scheme, which they even point to, is that the price of the visa would be pretty high. But they don't follow up on that and realize that this means a return to "black market visas", aka illegal immigration and labor of those who couldn't get a job paid well enough to justify a visa. Meanwhile if you had means and the will to effectively enforce the prohibition of that, you don't need the market scheme to begin with. So you just end up with a perhaps more streamlined version of the current system with similar problems.
Well, Yeah, I think that it would be an improvement over the current system in the sense that it will reduce the amount of pressure on the southern border by giving more options to at least some would-be aspiring migrants. Though you're very much correct that there's going to be the black market issue here for those who don't qualify--and I mean who are unlikely to ever qualify to come here legally. If they can't come here legally now but could in the future, then many of them might perhaps prefer to wait than to try coming here illegally.