i don't think that's the reason.
It's not what they think people want, it's about piracy and whatnot. With a SD slot, it was much easier to sideload apps, which would mean that there is a chance of people not buying apps and whatnot (because they can just download the APK to the sd card).
That being said, it's still probably possible with on board memory, but it's not as easy as just putting the APK on the sd. It's still fairly easy to sideload, but I think they just wanted to take out one way of doing it.
When I was testing my game ported onto android, I used to load up the apk on the sd and put that on my phone because it was really simple...now I probably will just email myself the apk if I choose to upgrade from the Note3 :l