One word: Term Limits...... LOL
The problem with the Senate is that they are no longer the voice of the states. The 17th amendment was very bad for our former constitutional republic.
There are those who would argue that cars don't need brakes either. I suppose if you drive off a lot of cliffs, brakes would seem to be a bit useless.
The founding fathers did not create this Senate, politicians did.
Originally, Senators represented the States interest. They were suppose to be the balance to the "people's" house.
In the early 1900s it was changed so Senators were elected by the population, and it has been down hill since.