Very true, it depends on your product though. If your getting a lot of your business through things like adwords/search and occasional articles/ recommendations your exactly right. Although if your developing something big the first impression is going to mean a lot. Take something like Google Buzz (admittedly even bigger than the range I'm advocating it for), I think that kind of first impression, where the service is all over the tech media and being talked about in social media, the first impression is going to mean quiet a lot in terms of future adoption.

Another example, Age of Conan, great game idea, early execution was off and it set them on a path where they were never really going to get back to initial subscription numbers no matter how much effort they put into the game.