I disagree that voting based on party lines is stupid. Given the immense power transparent congressional voting has given party leaders (in addition to lobbyists and organizations prone to intimidation such as the NRA) party lines become very important. There isn't a lot of deviation from party voting these days because of the sort of pressure party leaders are able to put on other representatives to vote with the party.

This means that I'll generally want congress to be filled with members of the party I most often agree with so that their bills have a better chance of passing, as it's the best indicator of how they'll vote, regardless what they themselves say or believe. Of course I also want a president who is a member of my party so that he won't put roadblocks in the way of their agenda and so he'll maybe get a chance to appoint a Supreme Court Justice or two.

Party does matter, but it's not the only thing that matters.

When party lines really don't matter, though, is during general elections. That's the time to focus inward and make sure we're actually getting our best candidate.