Of course Treemen are worth the points. too many players see the points cost of a model/unit and believe that for it to be effective that it must kill at least that many points. This is a complete falsehood. If a unit/character doesn't kill that many points, but survives, and holds up, helps kill the enemy so that the game is won hasn't it served it's purpose?
Treemen are hard to hurt, let alone kill. They are the ulitmate anvil to the Woodelves Hammer. If the enemey sends his best troops/characters at the treeman in an effort to destroy it then isn't the treeman doing a good job? Maybe 2 or even 3 times the points cost of enemy may be sent against the Treeman, maybe killing it, maybe not, but no doubt taking them out of the game for the most part, allowing you to destroy the rest of the army piece meal, or to grab enough points and hide.
The other thing about Treeman is that they shouldn't be used against ranked units by themselves unless you want them to hold the unit and not destroy it. They are great at taking out characters, only average at fighting units.
Does a goblin player who loads up on Fanatics, but they don't kill anything whinge or moan if the fanatics cause his opponent to redirect his movement, stall, change plans etc.
To truly get an idea of how effective a troop type/model is you must look at the overall effect on the game, not the points.