Hmmm... if pressure directly correlates to light levels, does that interact at all with non-natural light or spells?
There are interesting implications to be had if, say, a light spell can bring a bubble of safety among otherwise deadly pressures, or if a darkness spell causes damage to those caught in it. Even if magic light doesn't work for this, there might be some novel industrial processes enabled by isolating items from all light to invoke massive pressure. Diamonds, for example, might be forged by applying sufficient pressure to some carbon.
On the other hand, if this is the case we should probably be checking on our trade goods in their steel boxes to ensure they haven't been crushed.
Something as short-lived as a light spell would not normally alter pressure, it takes years or even centuries for it to shift with ambient light levels. That said there are magic items called Delver's Lights that work much faster and do create zones of safety, but it's a brave traveler who trusts them too far. All it takes is one dispel.