It's not bad UX. Apple provides three other app installation options that don't create a new disk on your desktop. The fact the the developers don't want to use

It's not bad UX. Apple provides three other app installation options that don't create a new disk on your desktop. The fact the the developers don't want to use those 3 methods is not Apple's fault. Blame the developers for that. Now if Apple where to follow you suggestion and lockdown the app installation for better UX, there would be pitchforks everywhere. In fact, the pitchforks where out just last week for this issue.