I am sure people get too fixed on the "certified max depth" - your experience and actual diving is what should be determining what your max depth is and not a cert card.
For example, as I got more experienced and started diving a bit deeper I found I was pushing my safety margins diving a 15+pony and so moved to a twin set. Then I found that to get any bottom time I needed to do some deco and so I started looking at adv nitrox and deco courses.
It just sounds as if there is a tendancy to let your diving be lead by the cert level rather than finding the diving you are getting into warrants more skills than you have.
Also, ta for the chance for me to talk abt me again - one subject I love.