For gmail I use Apple mail ever since and I don't care at all about the web interface. Hence everything stays as it is because Apple Mail is probably the less updated software in the world.
Calling it "the less updated software in the world" shows why companies do even more frequent updates, even when they aren't needed. To avoid appearing stale.
They have understood something other tech companies are yet to learn: Noone uses your product because you're so modern or progressive or slick. Your product is a tool, not design porn to wank off to. Apple fanboys are overwhelmingly fanboys because Apple produces reliable tools they use to create stuff themselves, not because they dream of glossy icons at night.
We can see what happens when a company decides to degrade a "useable, reliable tool for creation" with stupid design/UX decisions in the Thinkpads, which had a fanboy group that is currently diminishing because anything post-T520 is just a sad excuse to the "reliable tool"