It actually didn't make sense (P2P) after a certain point. There was a huge Skype outages because of a SuperNode back in 2010 when it was P2P. The problem was a

It actually didn't make sense (P2P) after a certain point. There was a huge Skype outages because of a SuperNode back in 2010 when it was P2P. The problem was a lot of super nodes ended up being desktop hardware that simply couldn't handle the increased load, likewise, since most desktops are behind some form of NAT or firewall, not many clients are eligible to be supernodes, meaning fewer and fewer reliable hosts to act as supernodes. Not to mention the additional load it creates for the user of the machine when it becomes a supernode. The solution was simply for Skype to host its own super nodes. That was the original reason. Of course, now there is also the wiretapping concern, but I think its high time something replaced Skype anyway, that either doesn't require the supernode weakness and possibly open source so the encryption can be ensured sending your private cert/key over to the centralized node/servers.