I can only guess...

How about: The plane operates at, or closer to, minimum drag conditions if it doesn't have to fly with loads of elevator trim. That must be worse than the cost of power wasted by pointing the engine down.

ummm... a plane that is climbing, but not accelerating, has no "excess" lift. So we can't really say the wing's lift is in excess of that required to support the plane's weight, hence it climbs. At least not when it is a steady state.

When power is applied, the plane will speed up, react transiently, and the balance of forces will reestablish the plane in a climbing condition. The engine is delivering power in excess of the rate at which it is being sapped by drag, hence the plane is climbs. I feel much better now.

cap, this is for fun, and personal edification, not animal cruelty. If we stopped beating dead horses this site would shut down. Not exactly the cutting edge here... these horses were dead from the get go.