In real life no one will notice the difference. And the favicon is now flat without a bevel. That would have taken about 10 minutes.
Seems like a lot of work for nothing in the wordmark change.
In addition to helping implement the brand in the short term across teams and products, a redesign like this also gives the brand a clear foundation on which to grow and evolve, instead of being fragmented.
A huge part of being a designer in a large company comes down to figuring out how to design systems. The impact of adjusting 4px probably did occur in 10 min in a design program. But the conversations and thought that went into the overall system took far far longer and required a huge amount of knowledge of how systems like this are used and implemented.
It's a very subconscious thing, how we appreciate two similar things with slight changes, and often we would struggle to explain why we feel that way. It just 'feels' better.