1. Becoming A Teacher
If you plan on becoming an ikebana teacher some time in the future, then you definitely need to get certification...all the way up to getting your Teacher's Diploma 4th grade, which is the minimum rank required in order to teach. Certificates are issued only out of the Sogetsu Headquarters in Tokyo. When you get your certificate, that means that you are duly registered with Sogetsu Headquarters and they can keep track of your progress. When the time comes for you to become a teacher, the headquarters will be able to accredit you based on your officially attained levels.
2. Recognition By Others
The teaching curriculum of the Sogetsu School is centralized and governed by the Sogetsu Headquarters in Tokyo. All Sogetsu teachers use the same textbooks. In this way, standards are upheld and the skill-set for each rank, whether attained in Tokyo, Toronto or Rome, is kept uniform. Any Sogetsu teacher will understand what you have been through just by simply knowing your rank.
This can be especially useful if you have to move and change teachers. Say you received your First Certificate in Sogetsu (like the one pictured above) here in Halifax. Then you move to Vancouver but still want to continue your studies. When you find your new Sogetsu teacher and show her the certificate, she will more or less know your skill level. She may ask who your previous teacher was and maybe contact her in order to better understand your training. She may also ask you to create a few test arrangements appropriate to your level. BUT, you will not have to start from scratch and most probably will simply continue from where you have left off with your previous teacher.
If you want to work as a florist or floral designer and would like your prospective employer to know that you know ikebana, then the certificate would definitely help! In Japan, people in the floral industry will certainly appreciate the kind of sweat and tears needed to get such certificates! Outside of Japan, we cannot really say... But compared to the person who claims to know ikebana just because he attended a few workshops, you will surely have better credibility with an official certificate!
3. A Sense of Achievement And Belonging
A certificate tells you that your school recognizes your accomplishment. It also puts you in the company of all the other persons around the world who have gone through the same training. Even if you do not intend to use the certificate in a practical way, the sense of achievement and belonging it brings could be worth it!