Most battlefield and military tactics are made by people who have nothing but their own physical bodies, physical handheld weapons and physical projectile weapons to work with, and have to finagle how to use these to their advantage against other people with the same types of weapons at their disposal?
In Thedas, most mages have enough firepower destroy an entire village in one go. To pretty much rain fireballs, ice storms, death clouds, physically and mentally weakening spells, etc. at large groups of people from a distance, before they even get close enough to touch them. And they have so many diverse spells with different abilities; elemental blasts, defensive
And against common soldiers that would be enough. But you're not facing common soldiers, are you? You facing templars who are trained to counter your powers and kill you.
Going by your description, you'd think mages were untouchable juggernaughts. Take a look at the Circle in Kirkwall and see how well those mages with all their power and no fighting experience or knowledge of tactics fared.
And if there were more than seven or ten mages, they could have thrown enough firepower to wiped out the opposing army before they got close enough to chop their heads off. Individual mages have enough strength to flatten a village, remember? Imagine a whole village-full of mages, all attacking and focusing their strengths together. Or, you know, using the defensive and healing spells on themselves and each other.
Sure they can. And all of that can be neutralized. And getting mages to focus their strangth together takes pracitce and experience. Battles are chaotic afairs where unexpected situations can and often do occur. A trained combatant can quickly adopt and respond to the new situation. A mage that spend his whole life locked in a tower, reading books and practicing magic that may or may not have a practical application on the battlefield cannot.
Did we actually play the same game? Because I played as a mage in DA:O and by less than halfway through the game, I no longer needed party members or meat shields to defend me. (In fact, one of the most common praises/complaints I heard about DA:O mages was how much sooner and more easily you could solo through the game than the other classes.) I could cast powerful AoE and crowd control spells and wipe out, or at least severely weaken huge crowds of enemies before they got close enough to do damage. And for those few who still survived the onslaught, I cast health/mana drain force fields around myself, so they became a lot weaker and a LOT easier to pick off in hand-to-hand combat. And that's before I learned blood magic and the glorious Blood Wound...
Do I seriously need to explain to you the difference between a mage protagonist and an average npc mage in a computer game?
Ok,here we go.
As a protagonist you have all the advantages of your class and none of the disadvatages, because the game wants you to feel powerful without having to worry about the consequences that come with using that power. You can cast spells without worrying about becoming exausted, drink lyrium potions like there's no tomorrow and never become addicted to the stuff, enter the Fade as many times as you please and never run the risk of becoming possessed. Hell, you can use blood magic without anyone blinking, let alone calling you out on that.
Effectively, the game made you a superman among ordinary humans, and expect everyone else to be the same. Except they aren't, because then you'd be just a normal mage and where's the fun in that?
And of course, it'll ALWAYS be like that. They won't learn, adapt to their new situation, use their environment to their advantage to make up for not having the Big, Strong, Clever, Experienced, DESPERATELY NEEDED army general to protect them. Like guilla warfare: attacking from a distance, from hiding, from elevated or fortified positions. And the suppor they have now, between these two games, is the amount of support they will ALWAYS have. They can NEVER gain new allies. It's completely impossible for an experienced commander to join their side, or even find an experienced commander among them, etc.
Nope, they'll always be inexperienced, unsupported children that are incapable of learning, adapting, or gaining new allies, and will just sit around sucking their thumbs like two-year-olds waiting for the Big Strong Soldiers to run up and lob their heads off.
Oh, they'll learn. Every has to learn if they wish to survive. But each lesson will be played for in blood and how much of that can you lose before you're hopelessly outnumbered?
And who's going to ally with them? They're a minority in a world that hates and fears them, and that fear won't simply vanish after a mage victory. Let's say they do manage to learn, adapt and ultimately defeat the templars? What then? Do you imagine them peacefully settling down among common people, to be greeted with open arms? Oh, I have no doubt they'll try, but eventually bad things will happen. Things that a poorly educated, superstitious peasant cannot understand. Animals may get sick, crops may fail and people will look to someone to blame. And that mage living nearby will be a prime target. Angry mob will attack him, most likely get fireballed to death and the authorities will be alerted. And we'll have another war on our hands, except this time it'll be mages vs the rest of society.
And before anyone gets the idea that I wish to see mages slaughtered by templars or anyone else; I don't. However, I'm not so naive to think that a rebellion will solve their problems or make the world more accepting. I also realize that templars are needed and having them removed, or letting them slaughter every mage they can find, isn't going to help matters either. The only plausible long term solution to this mess is for both sides to stop fighting and reach an agreement that can serve as basis for building a more just and honest system in the future.