...Plus, I would have to buy an additional controller for $50. So, console game = $59 + $50. PC game = $29.
You only purchase an additional controller once, so including it in the cost of the console version while not including it in the cost of the PC version is nonsense. Also, Lego Pirates is $20 on all 3 consoles and $30 on the PC http://www.amazon.com/LEGO-Pirates-Caribbean-Pc/dp/B002I0JJMK.
PC games get updates and bugs get fixed. My daughter and I recently played Lego Pirates of the Caribbean on Wii and it was practically unsolvable with 2 player co-op. It kept locking up with no way to update it or fix it. I wish I had bought the PC version.
The Xbox and PS often get bugfixes as well. For most multiplayer PC games, if you want to play with your daughter, you'll need to buy a second PC (and 2 copies of each game as well). Kinda makes that $59 you spent on a second controller look like chicken scratch...