Then it is important that the emails that are collected are then used for doing that. I have yet to receive anything more than a "verify your address" email based on submitting mine to any of these pre-launch email collection sites. Nobody has communicated with me about features, or tried to use my interest to help develop their brand. Perhaps if that were the case, I'd look upon these pages more favorably. But my thought in general still stands: If you don't have anything to share, you possibly should reconsider collecting emails until you do.

I agree, pre-launch sign-ups are important but there needs to be engagement with the emails collected until the product is ready. Fab did a great job with this by creating a mood board that allowed folks to post stuff they like before their actual service launched.

And what does it do for the user? "I am going to build a space ship for less than $1000, give me your email address and I will let you know when I am ready." What did that just do for you that it would not when it is actually done?

Lots of information about who and how many might buy your spaceship, helpful in decisions thought the design and manufacturing process, a group to announce product and beta launch to, leveraging months or years of long tail attention rather than just launch day, ...