Agreed, this complete puts me off too. Was initially interested but that evaporates with having to register.
It's the same with me. If I am using a really early stage app and actually helping with testing it the last thing I would want to do is to pretty much sign up for it with my email unless I desperately need that app.
You need to freely provide the download. No one is going to give you their email address to download what should be an open source project.
But I completely understand you. I hope Marta will be available for everyone quite soon (maybe at the time of 0.2).