Thread split, since it was offtopic.
Time Stretch, Mindslaver, Insurrection, and Myojin of Night's Reach have all been given consideration for banning, several times... and none of them were that close.
These all fall under the class of "Chicken little" cards which routinely get people up in arms but actually aren't bad for the game.
Yes, Time Stretch is incredibly powerful... it's MTG's equivalent of the AC-20, so it should be. At ten mana and sorcery speed, it does what it should do... give you an enormous boost, but unless your opponents are atricious you don't win the game every time you resolve it. You'll certainly be in much better shape than you were, and if you were in a solid position, and you have some kind of instant win combo available, and you resolve it... you'll probably win: your opponents should have stopped that snowball long ago. If you were in bad shape then your ten mana sorcery will probably catch you up a long way, and if the game was stable you should be the clear leader. Seems fair.
If, in YOUR meta game, a resolved Time Stretch is always game over... then I'd lay good odds your meta is full of people playing naked combo decks and no one is playing enough good disruption.
The other cards mentioned are similar.. for a huge amount of mana, you get a huge effect; an effect which will do a lot to help you win the game. Sounds about right to me.
Norytt once said that EDH is "Battlecruiser magic"... a phrase that I really liked. 8+ mana sorceries are the cruise missiles of magic and if your meta is a simple "who fires first", then yeah... they're probably game ending and you need to evolve. Better armour, maneuvering, countermeasures... take your pick. But don't complain because you decided to sign up for the the Assault arena and someone cored you with one good broadside.