What other ways to freely rotate part other than using scroll wheel button?

I think you're mixing up rotating environment with rotating part. The way it works on mine (and it always work like that) is left click and hold on part is moving it aroung, right click on part and holding is rotating it around 'click' point, and the scroll rotates whole environment (camera view inside your assembly).

Spacemouse

Or get a mouse with extra buttons and program one of them to be middle mouse click.  (I did this with a mouse that had a button right beside my thumb, it worked very well.)

To my knowledge it hasn't changed at all.  I've been using SW since 2006 and I can rotate my part the same way.  I do use a 3dConnexion SpacePilot but I can also rotate as needed with my middle mouse button.

Steve C

Nope.  Never worked like that.  It's always been middle mouse button (which is typically scroll wheel).  There is a command you can activate (View->Modify->Rotate) and then get the behavior you're looking for.  You could map a shortcut key to that. 

I've always used a spaceball or other 3D controller.