Both methods have their merits, I have other minified projects which do not include usb-to-serial. For this project which is intended as a replacement for my prototyping arduino's not necessarily as a project itself.
those without top notch soldering skills? Personally I'd phrase it more like "those without proper smd soldering tools". Maybe a pro can drag solder a 100pin qfp (I can't) but a novice can easily solder a FT232RL with a hot air rework station ($50 on ebay) or a $20 target hot plate.