Whatever technical reason they give, it's bs. The real reason is lowering cost and raising margin, except for Apple (they make ungodly margin regardless). By selling higher flash, they make better margin. The "stripper" devices are the ones w/ 8/16GB. You just saw Google lower the price of the Nexus 7 to keep in line w/ Apple spec wise. Price wise, it's not even close.
What happened to the 8GB Nexus 7 that I have? That should be $150
I don't have any media on the thing and only have 2GB free. 8GB is just not enough and they know it. A true stripper.
As to the Nexus 7, I don't care because it's wifi, and if I'm not on wifi, I don't use it. If I really need extra storage, I plug in my OTG cable and have 32 GB in an instant. It's not as elegant as sd card, but this is where we have gone. It may seem silly to this bunch, but outside this the technical crew a very small portion of the population even know they have SD in their phone or how to use it. They only know what's quoted on the specs.
In fact the times that I want to use media, is when I'm "off the grid". Planes, away from home, trains. I don't have unlimited data, so by playing my media in the cloud 100% of the time can get expensive.
I read a blog where Google said monolothic storage reduces support calls (which it probably does), so I get it. But they too want everything in the cloud, which is at odds with the carriers who tax you heavily for using the cloud today.
Answer: Use OTG cable or something like the Kensington Wi-drive.