What do these exams enable you to do/become?
I expect the experts will be along in a bit. The Modules to me provide a reasonable route to the accurate assemblage of knowledge in useful and/or vital subjects related to beekeeping.
From the knowledge gained - and there's lots of copy-paste, inaccurate and questionable stuff on beekeeping out there on the web and in books (even allowing for acceptable viable variation in things such as queen rearing and swarm control) - comes the ability to reason, assess, discuss, evaluate etc and be a better beekeeper as a result. The Basic really is a gateway to the fundamental tools, beyond that is a lifetime of learning however you choose to do it.
Now, for some, they are disciplined enough to pick the right books and learn without a goal in terms of time and level. Great. Others prefer a set deadline for that learning. At the end, either way, by learning about disease, behaviour, Honey regs, bit of botany, bee breeding etc it will up your game as a competent practical beekeeper. And drastically reduce the questions on here
As for "become": a confident tutor or mentor (with appropriate practical experience), FE tutor, masterclass tutor, employed in beekeeping in certain environments. A question you need to answer yourself - if that bit is important to you.