Why is Skype forcing a software upgrade on all of us?
The downside of this for Microsoft/Skype is that they can't get people to use all their new services - or see their new ads - if there are so many older versions.
Similarly, they can't move to new technical architectures that may provide better service when they have to also support a long history of past releases. (For example, their move awayfrom the peer-to-peer architecture that was their original highlight to more of a centralized "cloud" architecture to provide better support for mobile clients.)
Ed: does not mention surveillance aspects of Skype (as confirmed by Snowden) and does not mention FOSS or surveillance-free alternatives.