Wirelessly posted (BlackBerry8700/4.1.0 Profile/MIDP-2.0 Configuration/CLDC-1.1 VendorID/107)
The initial "launcher" holster decribed was released first, so early 8700 users got that and therefore have the "launcher" experience.
As takeshi mentioned, RIM released an updated version of the plastic holster, which is likely what you have. I got the "launcher" when I bought my 8700, and received the newer version when I got my replacement unit.
They included the soft platform at the top to help prevent scratches and also got rid of the tabs on the side which kept breaking off, therefore rendering the holster useless due to the extreme lack of grip (another small change was the absence of the tiny plastic ridge on the inside of the swivel clip which some users reported indenting their screen). Since they got rid of the tabs, the solid grip at the bottom is much stronger. But like scooter 2 said, the trick about it is grabbing both sides of the BB on the black textured portion (where the USB port and trackwheel are located) and placing one finger on the holster itself.
Once you know the trick, removing the BB from the revised plastic holster is very simple.