I don't get this obsession. If we were talking about a game where the enemies where controlled by a human, that would be one thing. But sometimes the similarity makes no sense - darkspawn aren't regular humanoids - and sometimes is actually lorebreaking - darkspawn cast using the blight, they don't use regular magic.
But ignoring these points - which in the end are a bit more nitpick-y complaints - why do we want the AI - which clearly can't reason or operate as a human does - to have given the same set of abilities as a person? Either it uses them right which means it's a race to who can alpha strike first, or the AI doesn't get to use some abilities.
Take Mana Clash. If enemies used it then combat would always just be a race to whoever casts it first. Or Mass Paralyse. Or Blood Wound.
Those aren't abilities that get used.
99 percent of rpgs out there lets NPCs and enemies use skills and spells that are common in the world the game is set it. Enemies are characters. People. They have learned things in their lives up untill you run into them. Hence why they are at a certain level etc. It all makes the world seem more real.
Sure, enemies should use those spells, if said person has learned them. That doesn't mean every mage in the game should have those spells, of course. Their "magic education" might not always be aimed at god-moding in combat.
The way it is now, with enemies just having 3 different attacks, no matter what level they are, they seem like a joke. They hold absolutely zero threat to the Protagonist, since the protagonist gets to have access to every ability in the world. We get a machine-gun, the enemies gets a pellet gun with 3 shots. That is how it is now.
There is a famous line that goes something like this "The strength of the protagonist is measured by the threat of the antagonist(s)". It is one that fits with most stories, really. What is happening in DA:I, though, is that The Inquisitor ends up being nothing but a Mary-Sue from the get go. He is more powerful than anyone he runs into during the game, simply because the enemies can't really do anything to damage him. They stand there, try to fight, and lose when their HP runs out. The player doesn't even need to put any thought into it when he kills them either. Since they have absolutely no abilities that can surprise him, or turn the fight in their favor.