Unless you're sending your link over a relatively short fixed-length limited medium like Twitter or SMS, there is no fucking point.
I've seen people post links to download apps, which go from their own site > some random bit.ly/etc URL > dropbox. I'm already seriously doubting if I want to run your app if you can't manage something better than dropbox file sharing, but to then rely on a bit.ly URL that could go fucking anywhere, when you're just putting the link on a webpage is beyond belief.