I didn't destroy it with my Paragon Shepard. I thought we could learn something from the Collectors on how to stop the Reapers. After the ending, and it showing the big red sun, I knew I made the wrong choice. Darn you Illusive Man!
I thought it would be extremely beneficial with the war against the reapers. I know it doesn't seem right giving that kind of power to the Illusive Man but you have to think of the greater good.
I always expected this game to kind of trick you. You can't let morals get in the way of logic.
But then I thought about it again. The average Mass Effect player would choose one side whether it being Paragon or Renegade and stick to it. Unlike me who is a little bit of both because I do what I thought was the right decision at the time.
But in the end I saved it just to see what would happen.
I also only play with one main Shepard, with both paragon/renegade choices determining the context of each situation and this is the only time in which I really regretted the choice I made, especially seeing how the Illusive Man was eying it at the end...
But hopefully there will be a way to atone it in the events of ME3, as I intend to use the only same Shepard through the finale!