The reason why "getting it out the door" is so important is because nobody behind the door generally has any idea about what people will really pay for. By making it fast (read: cheap) to make, if you find that you don't get it right, you can try again, and again, and again.
Now, you can argue that "they shouldn't be releasing without knowing they will be successful", but if they have the ability to see the future, they should just take that VC money and put it in the market. People like Steve Blank and Eric Ries have a lot of evidence how running most startups (software startups particularly) using a "build it and they will come" attitude is ripe with failure.
Now, if you are just building for fun, that's different. I knew a guy building a Dropbox clone in C. More power to him (though I wouldn't have touched it, because I think it is too hard to get security right all the time in a language like C).