I like pretty colors!
Well the main reason is the price tag, the b2's go for at least a couple billion each. RnD costs run in the multi billions. Stealth aircraft are super expensive to develope and make and most countries dont wana put that kind of money into such a specialized vehicle.
Also the Fighter designation for the F-117 is totaly wrong, its not a fighter, never was designed as a fighter, cant act like a fighter, and heck cant even engage other aircraft with anything other then mean thoughts. it should have been A-117 or B-117. Though they didnt want to call it B because most other aircraft with the B designation are all big :P, and A doesnt quite work as the 117 doesnt generaly attack tanks and similar military ground targets, usualy just buildings. So instead they went with F which is something it doesnt do at all :P Maybe they should have called it SSB-117 or small stealth bomber
but then they might get mixed up with the navy sub designations.