Permit me to use Minecraft as an example.
Easy mode, enemies do less damage, fall damage is the same.
Normal mode, enemies do medium damage, fall damage is the same.
Hard mode, enemies do massive amounts of damage, fall damage is the same.
If it's good enough to satiate the casuals in Minecraft then it's good enough for Dark Souls. Frankly if you reduce the amount of damage enemies do then it's difficulty would be greatly reduced. But I do get your meaning, the Taurus Demon (second boss?) the hit box is quite wide and will sometimes knock you off in a glitchy sort of way. It's not a well designed area for a fight, but it's not that big a deal.
However I do think that for Dark Souls, enemy attack speeds would likely have to be reduced.
Take fights like Ornstein and Smough, their attacks are so fast that it's basically an impossible fight for casual players. Also it was a popular player killing farm area, so anyone seeking help was often instantly killed on their way to the fight.
This was the fight that ended the game for me. I had been killed around 30 times in a row between the checkpoint and the fight by players invading my world, and wasn't good enough to solo the fight myself. It was brutal and unfair and just took all the fun out of it, most of the player killers would just 1 shot you, or were invisible, or would kill you before your screen had even loaded properly. I'd even bought a bunch of Indightments, however they seemed like a shot in the dark.
The pvp system in Dark Souls was crap and the lack of ability to ask for co-op help from friends also meant that the randoms for co-op were often useless especially in terms of tactics.
I did end up continuing to painted world, but the next time I got stuck I was just totally broken from my experience in Anor Londo and threw in the towel instead of looking for help.
Also! I hear that there was meant to be a timer between invasions, however my average time between being invaded was around 5 minutes, it would have been less but I had failed a few attempts in between. The quickest consecutive invasion was around 30 seconds, to who I'm pretty sure was the same guy (same armor and weapon). I died and instantly revived, spent humanity again, ran out killed 6 or so enemies... Bam! invaded and instakilled.
I know a lot of people who quit around the same area for the same reason.
If you want my opinion? Don't' do easy mode, but split it so there are separate modes for co-op and for pvp. That way you can get help when you want it and fight people when you want to... it would be a big problem solved.