"The Desktop API was created in 2004 and it doesn’t support mobile application development." So what?
Desktop users built Skype with their Skype-to-phone and phone-to-Skype (Skype Number) subscription money. We want what we paid for: Skype API, and whatever apps and devices are supported by it.
Mobile will necessarily have different apps and devices with some (perhaps) overlap. Developers should be courted to redeploy their apps to a Mobile API if they like, and if their customers want. Microsoft should leave Desktop alone, rather than dumbing it down and damaging ongoing Desktop product value.
Microsoft has been perennially wrong about product value. This is just one more bold misstep.
That's just the thing though, the customer base no-longer require the desktop API, because there is a new more attractive (mobile) market.
Whatever amounts of cash we threw at them in earlier years matters nothing, nothing at all.