I'm still not satisfied with the conclusion at which we have arrived. Game mechanics ya'll say? It wouldn't be hard to script it so that upon being silenced, if you clicked on any NPC, you'd get something like If ( OnNPCActivate == 1 ), Return or If ( OnNPCActivate == 1 ), MessageBox "You are silenced and therefore cannot speak".
It wouldn't be hard to enable that into the game. But since that's not what happens when you're silenced, I'm guessing silencing is something else and not making the Player unable to speak. Besides, if you know a spell well enough, you should be able to think the incantation without even having to say it aloud.
You think it was intentionally left out? In all my years of playing Elder Scrolls games, it has never crossed my mind to have that happen. I'm sure no one in the development team considered it either.
I've still never really bought that magic spells require a spoken incantation though. I can sneak behind an enemy, cast a spell, and they don't hear a thing. I've never heard anyone say any incantation while casting spells at me and I've never said any when casting spells at them. You'd think if it happened, and if it could be Silenced, it would be audible. But then the Dragon Shouts require incantations and they are clearly audible, even if they must be whispered.
I've always been under the impression that Silence is called Silence so people would know what it did. It's a popular term that RPG fans acknowledge as a spell that prevents their opponents from casting spells. The book, Silence, suggests otherwise but doesn't give a proper explanation to why no one says anything when casting spells, so I feel like I could take it or leave it, and I'd prefer to leave it and stick with what makes sense to me.
That's one of the things I loved about the Mysticism school was that its spells were unknown and possibly dangerous to play with. Pity they removed it from TESV Skyrim. I'll mod it back in come hell or high water. It's a huge part of lore and a large part of the Psijics' ways of life, damnit!
They did not remove it, it's just part of Illusion now for the sake of gameplay and convenience. All of the skills are there, they're still just as mysterious as they've ever been. Don't get caught up on the superficial things.