It seems to transform into its own thing, somewhat tangential to traditional email.

Email itself has transformed into its own thing, "somewhat tangential to traditional email". Email is now used for a host of interactions that extend far beyond its roots. GMail is adapting to meet those usage patterns.

I'm not calling your choice to move wrong - you may not use email for all the things the GMail is attempting to account for. But it would be foolish for GMail to stop adapting.