Leave politics to the politicians
2. Don't encourage rank and file Democrats to vote a certain way for the sake of winning elections.
#2 is a somewhat less obvious point, though still an important one none the less. Sure, Democrats want to win the general election, and finding a candidate who can defeat McCain is on the minds of many Democratic primary voters. However, when Democratic politicians encourage voters to choose a candidate based on electability, then they begin to drag Democratic primary voters down to the same spineless, soul-less, valueless level. Suddenly, not only do we have politicans who only believe in things in order to get elected, but not those politicians were nominated by voters who don't believe in anything, either. At that point, the party is really in a world of hurt. Both the leaders and the followers don't believe in anything except getting elected. That is not the image the Democratic Party needs, especially considering that only now is it recovering from twenty years of death by meta talk from the DLC.
"Electability" arguments piss me off. No one REALLY knows what makes a particular candidate more electable than others. Certainly not amateurs like voters. Chris states it very well here. "Electability" is the kind of judgment politicians make. So when you spend a lot of time focusing on it, you are acting like a politician.
Please, don't do this. We have more than enough politicians in this world thank you very much. We don't need even more mucking things up.
Voters are like jurors in that they provide a reality-check to all the erudite arguments that are the norm in political circles. Jurors take the facts and the stories the attorneys tell them, walk into a sealed back room and decide among themselves which one spoke the least bullshit. The same holds true in politics. Politicians and political theorists can argue all they want about what strategy does or does not work. But it is the voters who ultimately decide the validity of these arguments and they only do it in the voting booth.
Voters who spend a lot of time worrying about electability are just destroying their own unique ability to judge the candidates.