You obviously haven't played League of Legends if you think you can hide in a corner - it's a fairly fast paced, 5v5, small map game. I could just sit there, but past the early stages of the game, I'd have a high chance of dying.
Also, I open it while I'm playing another game because I decide I want to play it, and I don't want to have to sit there and wait when I can have it idling in the background to be used immediately after I'm done. It's not a horrible thing if I have to open it after, but it still seems like an oversight that it ruins what I'm doing for those 10-15 seconds, whether or not I'm playing another game. I can't /do/ anything else, because on any screen other than my standard 1080p monitor I use at my house, it takes up a good half of the screen space. I don't need to close everything else to play Tekkit properly - my machine is good enough that I can handle having it and many other things open at the same time (well, my desktop is - it's still being repaired, though), so I don't see why I should need to close everything else because the makers decided having the logo always on top is a great idea.
The_New_Pro:
That's not the point. The program being free doesn't give them the right to infringe on the rest of my computer use. Spotify recently had a problem where, if you didn't pay for it, ads appearing in the screen would bring Spotify all the way to the front. Many people were extremely angry about this - but under your logic, that would be perfectly ok. Just because I'm not paying for a program (which, by the way, the makers decided not to sell - I didn't choose not to pay for it) doesn't mean they get to ruin the rest of my computer use for a period of time.