One of the worst things you could do to your battery (phone, laptop, iPad) is to constantly plug and plug it; and that's exactly what a single port does for this one.
Wonder how bad the battery will be after a year or so of use
LiIons have no memory effect. Plugging and unplugging does nothing for them. In fact they actually do best at around 80% State of Charge. The constant charging and drain has little effect on them. See Tesla for an example of this.