This was the first thing I noticed as well. It was always somewhat alienating when encountering newer formats that were less friendly than what came before. I think TOML does a good job of taking what came before and bringing it forward.
Over the many years of the usage of INI I think occasionally we've seen developers add their own touches to how they support types, sections, groups, multi-dimensional arrays or other structures within config files that certainly indicated a need for some more standardized advancement here.
I really hope this gains a lot of traction, because there are so many scenarios where things like XML or JSON are forced into roles they really don't belong in.
One thing that I would say is that it might be worth indicating a standard header that can be used at the very least in cases when it is not stored in a file with a .toml extension. It would not surprise me at all to see TOML widely used with extensions that describe better the intent of the file rather than the format.
