These complaints are all over the place, but I'll address the main points.
1. Creatures and enemies only approach combat in one way, run and die on your sword. False
For one, there's archers that run and stay away from you to deal ranged damage.
Two, dragons fly around and evade, dealing damage from a distance, landing sometimes or when you force them to, and they can even swoop down and grab you for a kill, though rarely. Still rather simple pattern, but a big improvement for TES.
Three, mages. Definitely do not rush you and instead stay back, run away to continue dishing out damage, or backpedaling. Sometimes even summoning things to help. Both archers and mages pull out weapons at times when appropriate.
Four, Wisp mothers try leading you into attack with their pretty wisps, then attack you with copies of herself and the wisps in an ambush.
Five, vampires also try ambushing by disguising themselves as vigilants. Swarm you with slaves and zombies.
Six, Falmer actually ambush and sneak on you in dungeons, as do sabre cats, who are rather good at it too.
Not perfect, but Bethesda shows that they're improving and will continue to.
2. Next, the spider... really? That's immersion breaking for you, of all the things you could have said? Practically every time I've seen a spider, it's in a cave or dungeon with plenty of exposed ground areas a spider of Skyrim's size could have easily burrowed into. And there are a number of locations where the spider is up in the ceiling in a spider nesthole waiting to pounce on you when you step under it. So there you go.
Next, all spells serve purpose simply to kill.
Invisibility spell, you don't have to use this to kill... telekinesis, pretty much only good for screwing around, restoration, turn undead, mage light, detect life, detect undead, transmute, waterbreathing, paralyze, equilibrium, calm, clairvoyance, yadya. There's more but you get the point. While some of these surely can assist in killing, it doesn't mean that's all they're for. Which is good because that adds variety. You did mention light spells but you missed a lot.
And how is invisibility useless? I've used it to great effect plenty. What they did is make it to where you couldn't abuse it. If you're running around like an idiot, people should be able to notice you. But if you can actually sneak, this helps out a good deal. No need to care about light. Stealth also works well, too well in fact. Their problem is the stupid npcs, though even dishonored hasn't escaped that issue fully. Also, werewolf and vamp lord should satisfy people's transformation needs I think. Wolves don't attack you in werewolf form, you can summon wolf spirits, and vamps can summon gargoyles.
In summary, go sit down. Everything does NOT relate to killing. Illusion was practically made to avoid killing as much as possible. Try a little harder in your criticism, please. It's not like you have to look hard to criticize the game.