I'm not going to deny that Batman: Arkham Asylum was a great game, but at the same time, I have to disagree with most of the points you said.
One, most of the stealth sequences of Batman were performed by sneaking up behind guys and pressing a single "Takedown" button, just like this.
Two, there weren't that many stealth sequences. I mean, there were some, but there was a large portion of the game where it forced you to fight large numbers in open areas without too many things to swing from or sneak up from.
Third, it's not realistic for one person, no matter how good a fighter, to be able to take on 20 enemies. And hand to hand fighting doesn't really make that much sense in a more realistic setting either, because they'll just shoot you.
Lastly, if you put the demo on "Realistic" difficulty, it takes three shots to die.
Batman was still my game of the year last year. But I don't think comparing the two games is fair to either one.
I do miss being able to hide the bodies in this, now that I'm playing it again though.