Pretty much this. They cater to rich entities (people, corporations, unions, etc) to fill their war chests. IIRC, when they retire they get to keep whatever's left over in their war chest. I think that money should go back to their party or to the person from their party that said party hopes will take over for the retiree.
I like term limits as well.
Term limits are a terrible thing.
We need long-term dedicated 'public servants'. They're known quantities who want to keep voters happy with them, and they get to know how to get things done.
What term limits do is to turn politicians into lame ducks who have no need for your vote again, who are unknown people selected by the powerful interests to get backing and marketing, meaning they serve those interests and not voters. Elections will become meaningless voting for pre-selected hires by powerful interests more than now.
Anyone who likes democracy should fight term limits.
That's not to say there aren't problems with untouchable incumbency sometimes - but the way to fix that isn't term limits, it's things like campaign finance reform.
The idea that term limits will help with Congressmen leaving to become lobbyists makes no sense - it'll make the problem, which is a very bad one, even worse.
The problem of 'keeping campaign donations' when they leave is a non-issue.