planned design 'feature' on the 787 or is it a by-product of the condensation problem with some
PR spin to sell it as improved comfort levels
Other airplanes are made of (mostly) Al which corrodes and the humidity is kept very very low for that reason despite being far from ideal for humans.
From day one it was realised that the 787 did not have this issue and so it was planned to be at a higher level because that is much better for humans.
No conspiracy, no cover-up, honest.