Originally Posted by CollegeFlyer

This sort of confusion is what happens as a result of UA GAs and FAs referring to E+ seating as an "upgrade"--the misnomer causes other UA employees who aren't personally responsible for assigning seats to forget that Premier members and above are entitled to free E+ seating, as one of the benefits they earned with their status. If you're a Premier, E+ is not an upgrade.

So while the reasoning "if you want a better seat for sure, couldn't you purchase it?" applies to upgrades to F for elites, it's completely inapplicable to E+ seating for elites.