Character Height?
Door heights are liable to be quite variable, for the reasons you observed, (accessible doors have to accommodate all races) and that inaccessible doors can likely be scaled to different sizes, lots of “prop” buildings can be found at varying scales.
Doing a quick search I found someone has used a wall as their static measurement to compare the min and max heights of the various races http://i.imgur.com/kIo9z.jpg
I also remember this image which shows the min max height of every race. Though I don’t know where they got the numbers from as to my knowledge no mechanical height measurement exists in game. http://www.guildwarsinsider.com/backend/wp-content/uploads/2012/07/GuildWars2Heights.png
Excellent, thank you! I’m surprised to see that a minimum height Norn Woman is shorter than a maximum height Human Man or Woman, since that didn’t appear to be the case on the character select screen, but further investigation suggests that all characters are shown at a “standard” height for their race/gender. At least, guessing by the fact that my Max Size Male Charr Guardian and Min Size Female Charr Elementalist only look a tiny bit apart.