Uh.... because 4.1 was only released July 25, and it takes *at least* 2-10 days for a package to move from Debian Unstable to Testing.
https://wiki.debian.org/DebianTesting
Too bad there is not a magical website where you can get the newest version today.
Oh wait....
http://www.libreoffice.org/
Or you could switch to Unstable, or learn how to apt-pin, or switch to Arch, or or or or... Linux is all about choice.