> 3- Security: by this reasoning, desktops and laptops should move all to Linux, right? WP is "secure" because it does not have yet a decent user base to exploit. Make it popular and will be as unsafe as Android or Windows. Make Linux as popular as Windows is today and you'll see a raft of security vulnerabilities appearing from nowhere.
While security by low market-share is certainly a factor, WP8.x uses a sandboxed apps model which isolates applications from each other and the guts of the OS, much like iOS does and like Windows RT apps do. This means it's inherently less vulnerable to attack than anything where a privilege can be escalated, such as Win32, linux or Android.
I didn't quite understand your point about #2 either. If standardizing on a certain model Lenovo or Dell on the desktop is fine, why is standardizing on an HTC 8X or Lumia 720 not fine?