Slightly late to this party but I've been involved in quite a few incident investigations where aircraft have encountered CBs but didn't have the WXR on (or had the display dimmed) as "it looked clear".
Just because it looks clear out front is no guarantee that there's no buildups at lower altitude. It seems often forgotten that these buildups can still cause a some nasty problems for you.
-edit- I want to add, this post isn't directed at anyone else. Just a general comment after reading the thread.