well, should be easy. Mine was several years old and time helped seal it pretty tight.
The first time I opened it, it worked out okay. Next time, the case broke (at the top).
Agreed, should not be necessary.
However,
The air intake path is pretty much only really accessible by opening the case, and then the internal tube that surrounds the heat element. I do agree that in normal use, taking some care with dust, etc., no cleaning should be needed. But over time resins can back up and build up bit in there. Lint can begin to clog the intake itself; these factors may potentially affect taste.