First of all, reading comprehension is important. What I said is that the limitations you speak of had nothing to with Apple's SUCCESS or FAILURE.
Read in context of the conversation, this comment
If it was such an important feature, then apple market share wouldn't be what it is, while winmo is almost dead.
could be read to imply that the whole reason apple succeeded and WinMo failed was becasue of expandable storage. He may not have meant this, but I chose to take that as his meaning.
Whether or not he meant this, the point I made still stands. Apple's original success had nothing to do expandable storage because back then this issue was eclipsed by the iPhone's many other great features. This is no longer the case, Apple's current slide against Android is in part due to this.
I am happy your mother swaps her sd card, however, that is a non-typical user by any measure
By any measure? Certainly not by anybody's measure that I know of. I have plenty of non-technical friends. Like most smartphone users, they have been using digital cameras/camcorders/mobiles for years already. As a result they all know what to assume when they see MicroSD written on a box. MicroSD = expandable storage. This is not rocket science, it is common knowledge in the 21st century.
You say most people aren't bothered... have you looked at the survey at the bottom of this post? http://blog.laptopmag.com/windows-phone-7-traps-your-microsd-card-forever#axzz161QsEKje It looks to me like 80 / 100 users clearly are.
And before you argue that these people do not reflect the opinions of the average smartphone user, these people reflect your average internet user. I am sure that we can both agree that most smartphone users are savy enough to use the internet from time to time.