Two primary reasons both of them having to do with the SCOTUS.
1. They gave corporations the same rights as citizens
2. They decided that money = FREE SPEECH.
Those two anti-demoractic findings by the SCOTUS have scuttled the democracy part of this Republica and turned our governments into handmaidens for the extremely affluent.
So, make it illegal to receive any campaign contributions from anyone. No free Lear Jet rides. No funded fact finding vacations. Nada. Zip. That and the proposal by the OP should change things.
3. TERM LIMITS on CONGRESSIONAL SEATS