Yeah, it's pretty embarrassing and basically means that if you do something that might have a positive payoff in 5 years, you're basically doing an assist for the other side of the aisle. One party knows this and routinely passes tax cuts that are set to expire almost exactly when they lose power... The other side knows this but I guess tries to do the right thing anyway.
I'm sure there's some of that, but also ... a permanent tax cut comes with a negative budget estimate. A temporary tax cut doesn't look so bad. Then when it's time for the cut to expiring, making it permanent doesn't look as bad as it did when it was first proposed. Also, make the tax cut now, demand a balanced budget to make spending cuts when the other party is in power. </rant>
Most presidents assume they will still be in office in year 5. So it's not as bad of plan as you suggest. It's just risky as elections are not a sure victory for the incumbent.
