*Debate in progress.
*Default action 001.
*Check credentials.
Heh.
He's right though. Take Hitman as an example. That game is a stealth game first, action game 5th, and the tools provided allow you to see where enemies are looking, where you can move, where you can't, and allow you to devise a strategy in order to circumvent said obstacles. It, and almost every other stealth game, usually do a fairly poor job letting you know where the limits of a guard's view are, however, and usually provides for some pretty clumsy trial and error moments that don't feel like you're being stealthy, but instead makes the situation feel like you are exploiting the limits of the AI.
Let's look at the mario example though. You might not have specific arrows pointing to where you need to jump in order to hit a walking goomba, but the game tells you through it's own non verbal systems how you can preform special moves that allow you take different paths. The game never tells you can you fly below the platforms in certain levels of super mario world, It just shows you the alternate exit and lets you figure it out on your own. It's no different than what mark of the ninja does, the only difference being that MoTN shows you the sphere of influence you have over individual enemies that you will often have to use as tools to solve puzzles.
By allowing you to see the visual information, the sound information, the range of your weapons, your subweapons, your tools, you get to spend more time devising good strategy than wondering if that dog is going to arbitrarily see you if you're 1 step closer than you are. It takes the guess work out of the equation and makes the gameplay all about you figuring out how to make it in and out in a stealthy manner. It's never a glut of information; just because you know the limits of enemies doesn't mean that you're going to be able to simply skirt around them. There are enough situations where you're going to have to figure out how to slip right through a platoon of enemies without being seen, or you're going to die.
MoTN is, quite simply, the best stealth game in years because it manages to remove the guess work out of the equation. More games should attempt to emulate their system.
And if you don't like any of that stuff, Hard mode turns all the indicators off. IMO - it doesn't really make it more fun. Especially in the later levels where you have to deal with environmental traps.