Its always been a problem with VoIP I'm afraid.
Skype isn't true VoIP, its a proprietary software application so of course you can update/patch that rapidly and then claim "we've always taken security seriously"
The answer is IPSec. The answer has always been IPSec. The answer will continue to be IPSec although it'll take IPv6 to trigger widespread use of IPSec.
IPv4 is fundamentally insecure. It can't be fixed. It can be bodged (tunnels) but not fixed.
* rizla gets off IPv6 soapbox again
