We'll never know for sure the ramifications of the 17th, but if Senators had not been beholding to the whims of the people just as Congressmen are, had not been charged with spreading the wealth these past 100 years, I think it is fair to say our nation would be far different. The mindless urbanites would probably be fewer in number, for there would have been less money for democrats to breed them for the past several generations.
Under the federal system, there was feedback between the States and Senators. With the 17th, the feedback moved to between the mob and Senators. I just don't think the FDR, LBJ, Obama programs of spreading the plunder would have had a chance without the 17th.
Nor would anything which stripped state sovereignty. One could argue that the entire Twentieth Century would have turned out much differently regarding domestic policy and the effect it had on economics.