In short: in the TES universe, magic halts the growth of any kind of technology. Guns/cannons will never happen in a TES game. Stop suggesting it.
It would halt the path technology took on earth, but it wouldn't halt technology in general. It would just take a different path. They'd still want to come up with ways to make using magic easier, or the tools they make to be better.
Hold a staff a different way and it turns into a gun. So guns have kind of always been with us, just under a different name. If I were a mage that wanted to hit something long range with a staff, I would look down it to make sure I was aiming correctly. The aiming with a staff now mainly uses the crosshairs, but the animation is rather odd in that it looks like you just thrust forward instead of really aiming at anything. That works fine for close range, but for long range it's not practicle.
Some mage out there could easily make a variation of a staff that would be held like a musket, for long range shooting. There would be a small advance in technology for you, even with magic. Turning the staff into a more long range weapon. Its not impossible, technological advancements just wouldn't follow the same path as the path earth's technologies took.