In my opinion this idea of putting all bigger icons in the Treebar could be optional. Larger icons can be used in the smaller Toolbar and Treebar (default size). An option to resize the Treebar icons could be placed via the popup menu when right clicking on the Treebar.
The purpose of this change in the current beta is to make the icons visible on high resolution screens, as per the original post in this thread. I don't believe it would make sense to leave some icons small, and not visible, and other icons large. The interface, ie. icon size and visibility, should be consistent.
