The problem with encrypted removable media is that there is no standard whatsoever... So you end up with a small unencrypted partition containing a binary windows program that users are expected to execute in order to gain access to the data.
Not only is this completely unusable for Linux/Mac users, but in many environments you would not be able to install the software anyway. Plus it adds yet another piece of software which almost certainly won't be centrally updated and will sooner or later end up full of security holes.
USB sticks are typically only used when you want to transport data to a system which is outside of the corporate network anyway, since it would be pointless to use a usb stick when its much easier to copy data over the network... USB sticks are used when users have to take data off site, or give data to third party contractors...
Also every vendor of such devices seems to implement their own software, and i doubt much of it has been thoroughly audited, and there have been several cases in the past where such software has had serious flaws in the encryption it uses.
What's needed is a standard for encryption of removable media, so that an encrypted device can be connected to any computer and without the need to install software can be mounted upon entering of the correct key.