The framers gave the responsibility of selecting the members of the U.S. Senate to the state legislatures. This was a check against the federal government gaining more power over the state governments.
The 17th Amendment allows the people to elect U.S. Senators instead of the state legislatures. This has changed Senate races into popularity races. The U.S Senator no longer owes his seat to his state legislature. This has also indirectly led to higher federal taxes, increased financing of Government programs, and the individual states having to beg the federal government for money to fund local state projects.
Repealing the 17th Amendment restores the checks and balances that our Founders put in the Constitution between the Federal Government and the individual state government