Downloading an official file from the original application author is way less "random" and running without installation nor root is less crazy than you apparently think. It's how it has been working on other desktop OSes for decades.

See what Linus Torvalds has to say: https://plus.google.com/+LinusTorvalds/posts/WyrATKUnmrS

So sad ! A link to Google+, so I won't be able to consult it.