So, an ISP interrupting and breaking a customer's use of Skype to force their own paid IP phone service is fine by you?
First name an example of this.
Second, change ISP's.
Third an ISP deploying VoIP will typically segment off the VoIP network by VLAN or MPLS, such that any data apps do not 'touch' bandwidth allocated for VoIP.
Fourth VoIP bandwidth is typically very low, so bumping apps off for VoIP bandwidth is unlikey.
Fifth if an ISP doesn't traffic shape then Skype is more likely to be negatively impacted by restricted use of agressive Peer 2 Peer apps.
Next question?