You should probable post this topic in the Questar forum, where you'll receive a TON of responses! 
But while we're here, here is my
worth.
I think the main reason is the purported quality of every aspect of a Questar: the 1/10 wave mirror, the mechanical cleverness of the built-in Barlow and sun finder toggle switches, the sheer beauty of the scope with its gorgeous dials and dew shield, and even the old-school, leather case. Even if I wasn't interested in astronomy (visual or imaging), as a piece of art placing a Questar on a table is just as attractive as a good painting on the wall. It screams "look at me" as well as anything else in a house.
But the cheapest (new) 3.5" Questar is around $5500 I believe. Is that better than a $300 90mm Mak? 
I have an Orion Apex 90mm Mak. It gives me great images over a wide range of targets:
Are images with the Questar 20X better than these? Different people will have different opinions; for me, the answer is a definitive NO.
But dang, it is a beautiful scope! 