Scanner Limited To 300 DPI With Default Windows Drivers

I have an All-In-One Brother MFC-J430W (MFC-J430W | Multi-Function Centers | Colour Inkjet - Brother Canada). It is capable of scanning up to 1200 DPI. I loathe all the crappy software that comes with these things, so I only ever use the windows drivers, or I'll install minimal drivers if I have to.

I've used the windows default drivers with this one - it shows up in the device manager as a "WSD Scan Device". I think I had to install a brother driver to get the printer working though (the scanner worked with the default windows drivers).

When I use Windows Fax and Scan or VueScan, the max resolution I can set the scan to is 300 DPI. Am I going to have to install the brother scan driver to scan at full resolution, or is there a way to tell the WSD driver that this thing can scan at up to 1200 DPI? I've tried install just the brother scanner drivers from the CD, but I can't find a proper .inf file (i've tried them all). I don't have to install their whole crappy "suite" just to get the resolution issue fixed!

Win 7 Pro x64 SP1
MFC-J430W over WiFi