My wife hit her 500gb data allowance on her contract yesterday and was clueless as to how she had done it. A 'kids mode launcher' called Zoodles, which she thought was keeping the phone safe from tampering, was actually streaming sesame street videos from you tube. The app offered such a small selection of poor quality video files we had assumed they were stored locally.
I think a lot of people will buy these handsets blindly assuming they have an sd slot and not work out they dont till tjey get home. Think returns will be high.
For me personally an sd card does lots of things...it allows me to move my 'daily' music collection between my phone/tablet/car stereo/ pc with ease.... it means i dont lose my pictures if my handset bricks (which has happened to me in the past) ... android file transfer doesnt work between my mac and my s4 so its the only data transfer solution that makes any sense.
Im due a new co tract in mid may and will be looking to the release of the l4 or z4 to replace my s4... which is a shame as i was genuinely gutted when i finally saw the specs for the s6 edge.