The Pro Trail is aimed at the through hiking brigade.
Folk that use the tent for 100 plus consecutive nights on the trail not particularly concerned about maintenance.
Velcro is less likely to fail (without regular cleaning) than a zip , or to put it another way , zips are the first thing to fail on a tent apart from accidents.
As for the curtains , what you see is just an optical illusion* , the curtain is on the inside .
Here is a better view courtesy of Logan and BackpackingLight were there is a rather long ProTrail thread :

*OK , just kidding. The photos you have seen are of a prototype with the curtains on the outside.
The one that Swami used was made by Henry by hand so not the same as the production version.