You really need a PhD to distinguish between music stored on an sd and music stored on internal memory?

That google argument is marketing ********. Phones don't come with a free sd anymore anyway, so any person that is smart enough to go buy one and slot it in, can distinguish between music stored on it and music stored internally. If you don't want the extra space you won't find an indication of it's existence in the android software anyway.

Another reason to have an sd card reader is that many people fill their phone's memory slowly over the years as they use them. So why pay a large sum of money up front to have your memory empty, when memory price will probably have halved when you really need it a year later. Plus you get to keep the old sd for swapping.

Lastly it's upgradeability. For some people, being able to upgrade the memory is all they want. MHz and RAM (or lack thereof) aren't even noticed by most users, they aren't tangible. Storage is.