I've been working with this stuff for almost as long and here are a couple more of my personal favourites that haven't been covered already:
Not being able to debug a dialog is a major deficiency because of the extra time and effort that is necessary when you need to find out exactly what is going on.
How about a lotusscript class browser - ever had that sinking feeling when you pick up someone's (usually very clever and complicated) class definition to debug?
I think 'Rubbish' is a bit of a harsh description though. Flawed certainly, but it is easy to take for granted or forget all of the good points.