not giving away the source code has nothing to do with evilness.
no company would ever give the source-code away just like that. it happens quite rarely actually.
if it happens, the games the source code stems from are usually already quite aged or in rare cases the developer just has a momentary case of crazyness (i.e. goodwillingness

, or is just broke and hasnt any use of it anyway.
one of the few games with an open source code would be freespace two and apart from one or two others (i think some of the quake game source codes are free) i cant think of ANY game right now, that published its complete source code