While this simple reasoning is appealing, I have to disagree. Both its premises (Skype was peer to peer before MS) and conclusion (MS made it a client-server system because Evil).
- Real peer to peer on internet is not really possible, since most end users are behind NAT. Skype resorts to a number of hole punching techniques, but really only uses STUN/ICE, effectively using super-nodes as relay for sessions. This directly means that all these communication are transiting through a third party, and not peer to peer.
- Super-nodes used to be regular end users (with some simple algorithm to elect as supernode users with high up-time, high throughput. Fun fact: only windows client users were possible super-nodes). This model proved to be too fragile. In case the network falls down (which happened some years ago), then the super-nodes are no longer available, and get instantly DoS when coming back up due to every other node trying to get back. This is a vicious cycle in which the network cannot get back up. So for a long time now (before MS) super-nodes are just backed by Skype-hosted servers in data-centers.
- Thin clients are a real thing in e.g. the african market, where a lot of very old phones are still in circulation, no "apps" are possible. Think of your old Nokia 3310.
- Persistent group chats. Users wanted it.
- And on a more "political" aspect: MS needed to promote its cloud infrastructure (Azure), lower its physical resources fingerprint (get rid of Skype datacenters), and unify its technical stack (Linux/C++ now Windows/C#)
The old Skype for Windows was really locked and obfuscated. I remember that it would not even start on my PC with a debugger installed, even though it was not running in the debugger.
Then, Microsoft bought it and that all changed.