Tan,
I note your planning doesn't take into account passenger comfort.... So you plan to fly through the face of a Cb regardless of what your pax might think? Just because its within aircraft limits (or your own personal limits), does it mean its within pax limits? What a way to start a trip - "my captain is going to kill me!"
You think a Cb takes account of any planning you might have made for any eventuality?? Just because the crew in front got through OK, does that mean you will? How do you plan for nature? Do things never change between flight planning and the flight deck?
I'd argue that JW411 WAS there yesterday - were you? He sounds expereinced enough to be able to tell an active Cb from a bit of Cu, and they weren't small cells either. Cb activity in the South East UK yesterday was pretty exceptional, and being acutely aware of of what a Cb can do to your day were you to fly through it, why take the risk when its planted itself right in front of you? It'll move soon enough....
Tell me what carrier you are with, and I'll make sure I never fly with them.