What if the daylight saving's "extra hour" (that occurs in most of Europe between 02:00 and 03:00 (that is AM) in the night from Saturday to Sunday is important to the business you are making an application for?
How to make sure users can pick either a time in the first 02:00 to 03:00 or in the second? I know I can express it in offset datetimes: but how to show this to he user?
Do native datetime pickers allow this? I'm afraid not.
So I have (had) to roll my own :)
Also: native date pickers use the format of the browser, which may not be what the rest of the application was setup to. I takes away the "locale setting" from the app, to hands it over to the browser.
I like my browser in en_US, unless when dealing with date (I prefer yyyy-mm-dd like most programmers), size measurements (metric) and paper sized (I prefer A4).