I don't think this is as true as you'd think. And, I think it's become less true over time.
Old Key West, the oldest DVC resort, has between 0% and 30% of its rooms booked as studios on any given night. There are no dedicated studios, so it only comes down to how many lockoffs are booked separately. Riviera, the newest, has between 22% and 43% of its rooms booked as studios. That's a
significant change, and it's not because of prior constraints: both resorts are purpose-built rather than hotel conversions, and neither was subject to constraints imposed by an existing sister resort.
I don't know about anyone else, but a big draw of timesharing for me was to get away from vacationing in hotel rooms. I liked having a living space that wasn't also someone's sleeping space. I
really liked not having to share a bedroom with the kids. I liked having a kitchen and in-unit laundry. I know lots of people are perfectly happy having a hotel room or two on vacation, but that's just not for me. And,
to me, a DVC studio is a glorified (and expensive) hotel room.
Now, you can argue about whether Disney is pushing this change on buyers, or buyers are influencing DVC's decisions about resort composition. Personally, I suspect it is mostly due to what I think of as DVC's Original Sin. If you compare DVC
point charts to most other timeshare systems, DVC studios are under-pointed and the 1BRs over-pointed. In DVC, a >2x difference in points between them is common. In other systems it is much less. A spot-check of Marriott suggests a 1BR is a 1.4-1.5x premium over a studio, and that's at resorts that have the latter (many don't). In Wyndham, the smallest unit at a resort is typically a "Standard 1BR"---a smaller 1BR with a king bed in a private sleeping space plus a small living room with a mini kitchen and a pull out couch. These smaller 1BRs are usually about 20% fewer points than a "Deluxe 1BR", but the latter have a full kitchen and are usually quite a bit bigger.