First off and most importantly ISO 8601 is a standard for data interchange so being easy to parse visually and with a computer is a feature. ISO 8601 groups and sorts well without needing special rules and remains consistent all the way from the year to the millisecond. It is easier to parse visually when you are looking at a list of values, especially if they are similar.

Second "little endian" dates are inconsistent because the year is still big endian. If you want to remain consistent you would have to write the current year as 1720 (or even 7120!) because the years (or decades) are smaller than the century. To achieve the consistency of ISO 8601 with little endian time you would also have to write seconds before minutes and minutes before hours.

Right, very good point about the endianness of the year. Makes sense now.

A little pain converting to a non-stupid-date format now would result in less pain for rest of the history of humanity (so hopefully thousands of years). I think it's worth it.

Given that we use "big-endian" Arabic numerals, the ISO date format using those numerals makes the most sense.

Of course, when we remember that Arabic is right-to-left, we realise that in the original Arabic the least significant digit was read first ...