"What the hell is wrong with the US sentate?"
The US Government was AFAIK modeled on the 17th century system for running a town council.
It's never been seriously revised. IE a tacit concensus by a bunch of wealthy white men who might disagree on the details but all saw things basically the same way. Once one of them stops "playing the game" chaos can promptly ensue. And it has....
There is no age limit on Con-gresspeople or Senators,
Once they are the incumbent they are a b**ger to shift as long as they keep looking after the interests of their state/district. Accepting sacrifices due to changing national (or global) realities seems practically unheard of, hence the 2 (or is it 3) corporate bailouts of Ford and Chrysler.
Actual party line following seems to be virtually non existent. You get nominal Democrats to the right of Wacqui Jacqui Smith (Like the CA Democrat who loves the NSA) and quite relaxed Republicans.
IAN a Political Scientist. Indeed I'm not any kind of scientist.