Although only a minor inconvenience, having to enter your password every time you want to download a free app to your iPad is nevertheless an annoyance. It's good policy to require a password for purchasing apps, but there's no need for it for free ones. iOS 8.3 has finally addressed the issue. You can now require a password for pay app downloads, but not for free ones.
To turn off the password requirement, head to Settings -> iTunes & App Store and tap on Password Settings. You want Always Require checked off to make sure you still have to enter a password for paid apps, then you can toggle Require Password off under Free Downloads. Once this is done you no longer have to login to download a free app.