Actually, the first time you viewed the map, the left-menu was shown. You probably clicked the arrow to hide it. Then the next time you viewed the map, it remembered your setting and hid the menu. Just because you forgot that you hid the menu, does not make it a bad interface.
Hmmm. Glad you were looking over my shoulder to see what I did. Quite honestly, I so rarely use the GC website that you may be correct - most caching I do is with Cachesense on a BB 9000. My opinion is that it's a lousy UI and that is what it is. You're quite welcome to your own opinion...