Because with silent casting, your spells make no sound whatsoever.

Because

"ooo look glowing fireball coming directly at me, I didn't hear it, but I certainly saw it coming down from that hallway"

Personally this is why I think touch attacks should be brought back. Touch attacks, plus silent casting, could equal to a silent casting. But with a fireball coming down a long corridor I don't think so. It's just to noticeable, imo.

Hmm I do quite miss the touch spells.

Yeah, i guess it's the visibility of it. But the bound arrows have some glowing, so you could argue that it's not a million times different as an ice spike.

Maybe with silent casting the projectile could change colour, darker.

And good point about touch spells, those were cool in Oblivion.

With a bigger spell range and list there were many different ways to play a Mage in Oblivion.

With touch spells when I got a ridiculous amount of sneak, sneak up, touch. No one noticed me.

Also as a weaker rogue type, you could always drain their magicka, make their armor break, etc.

Spells are still glowy. So I always used ranged spells for more explosive mages or for more pure mages than I did as rogues and the like.

Silent Casting Should Not make the spell darker because Casting has nothing to do with the glowing ness of your magicka. And this is why I have said before in other threads bring back back attribrutes and skills and use Perks as special stuff.

Attribrutes and Skills determine what you can do, what you can't do, and how well you can do them.

And Perks should be extra, special feat like things that allow you to enhance your playability with those skills and attribrutes. For example if you want to play a Rogue Wizard, you'd benefit greatly from a

Silent Casting Perk

and maybe a

Contained Spell Perk

Contained casting means you can make your spells less noticeable, however, they wouldn't do as much damage because you're not amplifying them to their greater strengths. So it would make the spell darker, but it would also weaken it due to the fact that you're not releasing it's full potential.

Just, my two cents though.

I like this theory. It makes the most sense in the Elder Scrolls world

I hope all this will return in the next installment

Good question, it's probably for balance reasons. I mean a base X5 fireball is 200 damage AOE if it had a X5 multipler for the sneak. A Steel Dagger at 8 damage can only do 120 damage with X15 sneak perk (No double boosting gloves equipped) against one enemy.

Not to mention the Illusion silent casting perk would make this ridiculously OP.