If I email my senator or congressional representative, I get a cut 'n paste answer back from an intern saying they appreciate my input, then they put my address on their list to solicit for a donation next election. That's the full extent of my representation.
However, if someone calls from my rep's national party headquarters; someone whom he doesn't represent and is not qualified to vote in his election, that person will get the representative's undivided attention.
This problem isn't about "hogging seats," "new blood" or experience. It's that the people we send to Congress go there representing political parties and agenda driven causes rather than the individuals in their districts. The people who get the attention are those who will supply the money to get them elected next election.
The answer is simple. A Constitutional amendment that prohibits any donations to political campaigns by anyone not qualified to vote in that election. No businesses, parties, associations; only registered voters that the winner will represent should be able to donate. That simple change would send people to Congress and the White House that either represent their real constituents or join the ranks of the unemployed next election.