Jd, that was a desperate move by a company already in trouble, and not a cause. However they probably made that desperate lurch because they found the grown-up clients (politicians and other powerful persons) were leaving them for iPhones - they probably saw the biggest growth area for private messaging as teenagers and went for that.
They found a problem, but answered a different question. They should have been asking what the grown-ups want, and shoring up their top end.
Anyway, this is all in the past.
I can recommend Windows Phone to anyone wanting to make a change - although, to be honest, all major OSs cover all the BB requirements/functions.