First, it seems a little harsh to blame PB for your other Today screen plug-ins taking up too much room
With regard to the calendar pop-up.
This feature was added so users can quickly enter information on a specific day or choose to show specific days/ periods in the main window- it is not meant to highlight days etc (as you see in desktop Outlook).
You can highlight days and they will appear in the main window (it also has settings for 1 day/ 1week etc). You can then see the appointments you have on the main Today screen.
The reason for this is that to highlight all days etc PB would have to read the whole of your calendar information - which would slow PB down too much.
Remember PB is designed to be a today screen window into your main PIM - not a PIM itself. Although a lot of users decide that PB is so functional that they don't need an additional PIM such as Pocket Informant or Agenda Fusion.