Flat design may be less distracting to you but that also means it’s less clear, because there are fewer obvious demarcation.
I despise flat design, it’s downright awful design, and done for looks rather than functionality.
Even saying it’s “less distractive” supports this.
Microsoft also did this to obfuscate features, which is pretty apparent when you consider new users used to “discover” features via the menu system. I supported Office for MS in the early days, and this was a huge thing at the time. It was discussed heavily when training on new versions.
The ribbon is one thing, the flat design and obfuscating tools/settings are a far bigger issue.