Battery times are all over the map. You bring up a good question though. Maybe the open to users installing apps needs to go away? That's about the only way to make a device get a specific number of hours.

http://reviews.cnet.com/tablets/samsung-galaxy-tab-2/4505-3126_7-35477934-2.html pegs 6.2 hours under a very specific condition but then again, here's a link about how ad supported apps and checking email can drain the battery.
http://www.androidauthority.com/ad-suported-android-apps-battery-drain-65716/

The stock battery looks to be a 300 or so cycle battery so getting 50% of what CNET got when new means it's still considered good.
Bob