Empties input-boxes in firefox

I had a div that I wanted to display in a thickbox, the div contained an input field.

The bug I encountered was that even tho I in code set the value of the field the value would be emptied at the time thickbox displayed the div. This would only occur in FF and not in IE.

I debugged it and found that it had the value until this line of code was executed:
$("#TB_ajaxContent").html($('#' + params['inlineId']).html());

I fetched the latest thickbox from it's own website and looked, the line there read:
$("#TB_ajaxContent").append($('#' + params['inlineId']).children());

If I use the latter line it works just fine.
My question here is why?

It's a dead simple patch but before creating a patch I would like to know if there is any reason for the diff.