Let's be clear that this is deeply misleading.
WotC "held down" prices which rose by, what, 10%? And then increased them by over 70%.
What WotC are charging for Spelljammer is insanely higher than inflation. It's higher than inflation since the '80s, for god's sake.
And if they release 64-page books for $30 each, that's even more insane, that's HUNDREDS of percent. Don't lie to people about the numbers. It's too easy to disprove. When you lie to people's faces like that, you destroy your own credibility, and really should apologise for doing so.
(To be clear, if they release a 192 page book for $30, then they'll be forgiven, that's only slightly overpriced, but that doesn't seem to be the messaging.)