This is pure speculation, as I don't know much about the romanization beyond what I've heard in passing, but I imagine that switching to a completely new orthography is not something that people are going to adopt overnight, and it's probably a lot like when countries have made the switch from imperial units to metric. I know that 50 mph is about 80 km/h, but since I learned to drive in the US using mph, I have a much more intuitive sense of how fast 50 mph is, and if I hear someone discussing speed in km/h I tend to make a rough conversion in my head to understand it better. It's likely much the same for Kazakh speakers who learned to write the language in the Cyrillic alphabet. They might know that Қазақстан and Qazaqstan say the same thing, but it's difficult to make the split-second conversions between the two systems when you learned to write in one alphabet and you've just been introduced to the other.