While it may be a good idea, it seems a bit pointless to me, as any real hacker trying to compromise your site, will have Javascript disabled while making his attempts. Just pointing that out.
http://wordpress.org/extend/plugins/semisecure-login-reimagined/
I think you're missing the point. For me, the attraction is the ability to encrypt my password on the client-side, without SSL, for those occasions when I need to login to my WP site via an unsecured network. As it says on the FAQ for the plugin:
The point of this is to prevent your password from being transmitted in the "clear." If someone is in a position where they can learn your session ID, under normal circumstances, they'd also be able to learn your password. The proper use of this plugin removes that possibility.