Its even more basic. enemies only have 1-3 attacks\abilities. In DA:O the enemies had access to almost all of the abilities the players had. Made for more variety and less predictability.
Try doing that on the highest difficulty. Without setting up tactics. You would be dead as soon as you run into enemies that use overwhelm. DA:I doesn't even let you set up any tactics. And it isn't needed in that game either.
This. Enemy mages in DAO had the same spells I had (most of them anyway). Now it's fire mine, ice mine, fire mine, ice mine. Hut lock alphas used to have shield bash and war cry and other skills I had, now they have the same exact moveset as Every. Single. Heavy. Warrior. In. The. Game.
Humanoid enemies in DAI are the same five enemies reskinned to look different for every faction. That's basic. That's watered down.
An eleven heavy has the same moveset as a darkspawn heavy. This was not the case in past games. Horizontal swing. Vertical swing. Triple swing with guard generation for all.
As for tactics, the ai isn't good enough to replace them. In DAO if we'd had barrier I could have them cast it when I was under Melee attack if I wanted, or if I was surrounded. The crappy ai wastes it automatically before every battle, so i either turn it off, or I deal with the fact every fight starts with 90% of my barrier gone.
I know there are people here who truly love DAI combat, but the lack of tactics and the cut and paste bad guys aren't really something you can say aren't the case. Every archer is the same, every rogue with the exception of the red Templar variety is the same, every Mage has mines and a flying book. There's no variety in human opponents.