But it's small improvements that make the big difference. A small user interface element added or removed to speed up an interaction. An updated user experience so that data can be found or organized in a slightly different way.
I could pick on almost everyone of Google's products and have gripes about some UI or UX choice. Missing functionality here, overly complex there, etc. Every product has obvious low hanging fruit that could be improved.
That's what parent is referring to (I assume). There's no more micro-innovation happening. If it's not a change that makes 100 bazallion dollars, then it's just not a change worth doing, apparently.
A good example is changing the typeface of text labels in every product to match the new Google logo, which Google seem to have been continuously doing for years on end now. I would argue this even has negative value, as it creates a mix of two typefaces (Roboto and Product Sans) in every product that used to have one, which causes every future UI design decision to be saddled with the extra cost of deciding which of the two to use.
Protonmail understood this and catered to this need without much fuss: https://i.imgur.com/1ZhWOsC.png
Also the latest updates to Sheets in the menubars have been welcome
For products that are core, large UI changes tend to just annoy a lot of users, unless there's something really amazing about the change. Even then, people are hesitant to like new UIs. Engineers and designers definitely want to try new things, but balancing those against messing with UIs that a billion+ people use is hard.
My general take on drive and calendar, if they are trying to improve these cases for enterprise users. There's a lot of very non-sexy work going on to make these improvements, and they aren't always visible.