When using link to the course section in the breadcrumb, you find youself stuck in the one-section mode without pressing one-section button (until you manually click display all sections button). Note that course link in the breadcrumb doesn't have similar capability and will leave you in the one-section mode.
That is particulary bad because one/all-section buttons isn't very informative and clear and many newbies (i.e. students) don't know about them and coudn't return to the all-section mode by themselves. That's place an additional load on the teacher.
It will be better if this link placed you in this mode only temporarily or, at least, make course link switching you to the all-section mode instead.