People will get all bent out of shape because they don't have an app to control the colour of their LED lightbulbs, but they'll gladly put off work because the phone lacks the basic functionality that the OS of any mobile phone should have.
What, exactly, can Android not do with regard to file manipulation that it should? It's not like it's hiding files away from you. Android does things differently than BB10, just like it does things differently than Windows Phone and iOS. What you're complaining about here isn't lack of functionality, it's a change in workflow. And not even a permanent one - you can make it work the way you want!
If you only knew how many times I've had someone tell me they'd email me from the office because their "smartphone" phone is too fiddly or otherwise incapable of doing it.
And you think the problem is the difference between the document manager and a full-fledged file manager? That is, in a word, ludicrous. They can adjust to using an interface designed for a 5 inch screen and a touch keyboard, but if the file manager isn't consistent they just can't cope? The people you deal with would have just as much challenge on a BB10 device. It's not the workflow that's holding them back.
As I said, I regularly work off my phone, and the document manager suits me just fine. I obviously have the ability to go find a file manager, but I don't believe it would offer me an improved experience. the document manager is simple, straight-forward, and extremely easy to use.
Folks have been complaining for years that iOS didn't handle email attachments nicely. Apple finally got around to doing something about it this year, but it's still half-baked. Oh well, they can make their LEDs dance while they snapchat with eachother instead.
Should they make sure they get off your lawn while doing it?
I've actually never had snapchat, and I don't have any Hue lightbulbs, but let's say for a minute that I did. What, pray tell, makes your use case more meaningful than mine? Why must your experiences and your needs be transposed onto everyone else? Who are you to pass judgement on what everyone else wants to do with their devices?
People have different needs and wants from their smartphones, and for you to suggest that their needs and wants are frivolous because they don't align with your own is, quite frankly, asinine. You're not that important.