Oh, I don't know.... massive soundstage, for one, I suppose. Ability to accept the 12.5 arm (or other arms) at less total cost would be another reason, while still retaining an upgrade path all the way to the top if you- or a subsequent buyer- so chooses.
I have a bias that should be explained..I believe the Scout series to be a departure from the VPI 'sound'. Some like it, some don't. Whatever. The old 19 series were a stone cold bargain, IMO and shared the VPI 'sound' with the TNT series--on a slightly smaller scale, of course.
Try to hear a comparison, if you can. Could be ear opening

.
I doubt you'll be unhappy with any VPI product...I just like the larger chassis designs better. YMMV..
WEEZ