Yeah, that is not cool (missing USB cable). I bought the charging cradle (which does not include any cables/cords) and plan to use the AC adapter/USB cable that comes with the Vita to use with the cradle. So, buying this extra AC adapter would mean having to unplug my cradle and swap the USB over to the extra adapter (not very convenient).
I've decided the best option for me is to get a separate battery pack / charger like this:
Anker Astro 5600mAh Portable Charger External Battery Power Bank for Smartphones and Tablets including iPhone 6 / 5, Galaxy S5 / S4, HTC One (M8) and Many More
Then get a separate Vita USB cable to use with the charger. This gives me the added option of taking that combo with me on the road to recharge my Vita.