They are that thin because there isn't really a need or desire for them to be thicker. Having them thin makes them lighter and cheaper to manufacture (meaning more people willing to pay for them and carry them to bolt a route). They are plenty strong, being rated to 20+kN typically, which makes them not the weakest link in the system, so strength isn't an issue either.
In terms of the knife cutting a quickdraw, it's just not really a big enough problem. The way a carabiner hangs off it's not really on a sharp edge. In fact, the EN 959:2018 standard, which the hanger pictured is rated to, requires the edges be designed in a safe manner. You'll see aluminum carabiners get knicked up a bit sometimes so it's often considered good practice to keep the metal and rope sides of draws/biners separate/consistent. But it's not a big enough problem that climbers want heavier and more expensive anchors. If you're very concerned you can get Steel carabiners (Lots of examples) or steel insert carabiners (Edelrid Bulletproofs). I personally use Edelrid Bulletproofs on TR achor biners where the rope will be in constant contact and sliding over the biner. In terms of bending, that's all part of the strength rating in the EN certification process.
4.2.3 All edges that can be handled after placement of the rock anchor in the rock shall be free from burrs and sharp edges. The inner edges of the eye shall be rounded to a radius R of minimum 0,2 mm or bevelled to a minimum of 0,2 mm × 45°
If you want, HowNot2 have great videos on YouTube such a this one that show how hangers (and other climbing gear) break.