That's the thing. I don't think they want to discourage the sale of hoppers
per se, but I think they want to have crowds dispersed better among the four parks and all of them having good attendance and, more importantly, revenue generation.
A big issue is people going to other parks (especially DAK and DHS) in the daylight time and then going to MK at night. This creates just a massive crush at MK. Spreading those crowds around is a worthy goa; of course, having some sort of big night time area in DTD might help siphon off people.