Bram Cohen, creator of Bit Torrent, gives multiple reasons why developers shouldn't hack his network to get around ISP bandwidth restrictions in Obfuscating BitTorrent. These include:
* No benefit. Most ISPs don't discriminate against P2P (yet). Plus much P2P traffic can be identified by profile even if disguised.
* Incompatibility with other network clients.
* Any ISP caching (a good thing) would be useless.
* It's bad form and a poor use of developer time.

Those are true but generally apply to any file security scheme such as cryptography.

I disagree in that there are fundamental reasons, such as the right to protect one's identity and anonymity, that argue for security features. However the bottom line and driver should be consumer demand, not developer preference.

There actually has been little shift in the P2P market to more secure clients. So the market is not requesting such features.