Basically, certification is only needed if you are applying for a job as a BES admin, or required by your employer for promotion/etc.
I teach CompSci @ Trios College (
triOS College - Home), where we teach 3 BlackBerry courses to certification (BCSS, BCSA, BCSSS) - these courses are geared only towards email server administration/troubleshooting since most Exchange server admins are also BES admins.
The main reason we offer these courses is to give our students a competitive edge on the job market - they look better to potential employers when they are BlackBerry certified in addition to being Exchange certified.