Another thing I'll mention is that the whole "4e characters at level 1 are much stronger than other editions" concept is not as true as it used to be. I think a large part of this was the increased hit points, coupled with poor MM1 monster design. When you have a ton of hit points and monsters basically tickle you damage-wise, yeah, you're going to feel pretty darn immortal.
But times, they are a-becomin' different. With updated monster math, monsters are actually very scary now. People continue to believe that 4e PCs are indestructible, but things have really changed. I sometimes DM for a group of very casual players. I want to emphasize VERY casual. They regard D&D as a board game with a plot that they can play while getting drunk. One character is seriously named "Rape Clown the Unwieldy" and is basically a walking Michael Jackson joke. A few of the players are a bit more serious, but for the most part, yeah. Very casual.
When we first played, when it was just PHB, MM and DMG, fights were long and grindy, but they were rarely (if ever) seriously threatened, and rarely (if ever) knocked out. This was with casual players, VERY casual players, who do things like use poor (or no) tactics, constantly forget to use their Encounter powers or item powers, and generally waste actions doing things because they think it'll be funny or because they think it'll look cool.
They creamed MM1 monsters. They killed a Young Black Dragon at level 1 without breaking a sweat.
Now, though, things have been updated. And these casual players that barely understand the rules and have horribly built characters are no longer quite the swaggering heroes they used to be. Despite now being level 5, they frequently drop to unconscious. It's a rare fight indeed where I don't at the very least reduce everybody to bloodied. In the last adventure, I "called" the last fight because people had to go. I hand-waved it and said they defeated the BBEG and his coterie of mind-controlled orcs. They walked out firmly believing they would've won, so why not call it? Only I, the DM knew... they were headed for an inevitable TPK (it didn't help that the Longtooth Paladin entered the fight bloodied, refusing all healing, because he wanted to use his racial ability!).
So, yeah. PCs used to be gods. But then the monster's balls dropped. If you don't believe that 4e PCs can feel very much like zeroes, try running a level 1 Dark Sun game some time.