Excellent post today from Jordan Ragusa on the origins of the filibuster and more. I especially agree with his conclusion about the controlling importance of the "determine the rules" clause, which makes Senate Rule 22 clearly Constitutional.
Ragusa makes the point that legislative rules can be the result of historical accident or contingency, combined with path dependence. In other words, the whole "previous question" thing happens to Senate rules for no particular reason at all, sits there quietly for a long time, and eventually becomes the basis for filibustering -- and then stays that way because once something is in place it can be hard to change. What I'd add to that, however, is that general institutional incentives can tend to reinforce or undermine the path an institution has set on. For example, the House did wipe out filibusters, while the Senate did not. That presumably fits with the idea that Members of a chamber that is (1) smaller and for whom (2) constituencies are larger and less homogeneous will have greater incentives to retain individual Member influence. That is, they'll be less likely to trade off (relatively small) individual influence on a very wide range of issues for (relatively larger) influence over a narrow range of issues and practically no influence on the rest.
I'm definitely not saying that the Senate had to end up this way. Obviously, since the Senate has only been "this way" for the last few years, and there have been lots of "this ways" even in the last fifty years, let alone the whole history of the Republic. Indeed: one of the points that I've been making is that defenders of the influence of individual Senators should be first in line to support Senate reform right now, because the possibility of some sort of reform in the near future is large and so those who want to retain some form of filibuster should act to do so.
In other words: yes, reform can have unintended consequences and those are important -- but reform can also have intended consequences, and those are important too.
At any rate, read Ragusa's whole post, which is very good.