Look closely at the errata, though, because it's not all created equal. I think there's several types of errata.
For example, some errata is on the order of "replace the sentence about "At Will Power" to say "At Will Attack power". Wizards of the Coast makes Magic The Gathering, and because of the way that game is played, exact wordings are important, so this is something they do. Rewordings and clarifications make the game clearer and get the intent across better.
The second type of errata is "whoops, that's a typo". For example, when the View Object ritual was printed it said "1000 gp" for the component cost, and then in the listing it said "5000 gp". It turns out 5000 gp was what was meant. This is very important errata, because it could throw numerical and systematic values off.
Another type of errata is "we changed our mind"- the tiefling racial ability Infernal Wrath went from being some bonus damage to an immediate reaction encounter power. That's a big change- that's the kind of thing that changes how the game works. The motivation for this type of change is that "here's something we didn't think about enough originally- this way will be a bit better than the way we originally planned it". Would the original version of Infernal Wrath wreck your game? I tend to think it wouldn't.
Then there's the last type of errata- which is related to the previous type but it says "we designed this wrong. We'll have to fix it because it could cause a major problem if abused". This is where powers like Blade Cascade got tightened up. I think this is important as well.
In the case of the 4e Errata, most of the errata contains a sentence or two to clarify the thinking behind it. (For example check out why Careful Strike gets a damage bonus.. they explain that it makes it a viable choice compared to twin strike). This is good commentary,. you might agree or disagree, but it's usually interesting to hear why they changed things.