Most of time similar methods in other frameworks are used to retrieve exactly one value. Compare

    var data1 = element1.getHtml5Data('my-data'), data2 = element2.getHtml5Data('my-data');

with

    var data1 = element1.getHtml5Data('my-data')['my-data'], data2 = element2.getHtml5Data('my-data')['my-data'];

Even if you need two or three values from the same element

    var a = element.getHtml5Data('my-data-a'), b = element.getHtml5Data('my-data-b');

looks not worser than

    var data = element.getHtml5Data(), a = data['my-data-a'], b = data['my-data-b'];

Also in this example count the time needed for enumerating *all* attributes of an element and retrieving all `data-` attributes in order to get just few attributes with known names.

P.S. Everything is an object :)