Fair point but when you are told by a criminal lawyer you know that 70-80% of his cases involve finding technicalities to get charges dropped and most of these aren't taught in the course it seems about right. Many don't ever use units like Constitutional law in any great deph for example.
See I've practised primarily in public law so the constitutional and admin stuff is used rather frequently.
Hand me a criminal information and I would panic, consult textbooks, refer to anyone, anyone else who would undoubtedly be more qualified.
Still need to know the basics though to be able to give the qualified "this may involve the commission of an offence" advice.