Scheme to collect more personal data
I guess people who don't give out their Skype ID and accept the defaults can get a lot more people messaging and calling them via Skype. I don't have my Skype ID linked to my phone number and never will. Microsoft doesn't need to know my phone number for Skype to do it's job. I guess they want to be like WhatsApp and collect as much info as possible and be a conduit and keeper of a lot of information about a person and their contacts.