A mage isn't like a knife, or a bomb. A mage is like an scientist or an engineer.
For an engineer, knowledge + technology gives the ability to effect change, to light a fire, build a bridge, or create and deploy a nuclear weapon to wipe out a city.
For a mage, knowledge + a power reservoir (mana, lyrium, blood) give the ability to effect change, whether it's lighting a candle, building a tower, or causing the ground to swallow Arlathan.
The difference is that anyone can use science, engineering, or technology. Anyone can apply the basic tech of a few sticks, a knife, and a piece of string to light a fire. Anyone can learn to build a basic winch and crane to move blocks of stone. Anyone with the recipe can assemble a Qunari bomb and light the fuse.
Magic, however, is available only to those born with the ability, and that's what get people up in arms about it. If every person in Thedas were born with the ability to use magic, there wouldn't be this "mage vs templar" problem. The issue is, at its core, a matter of a very few people being born with an ability which makes all of them put together about as powerful as everyone else. In some places, the few dominate the many, like in Tevinter. In other places, the many dominate the few, as in Orlais. Both groups probably look at the places where there is balance and cooperation (like Rivain) and say to themselves "we ought to be running that place, our side should take over."
That's what makes this conflict interesting.