With revelations of NSA spying and some of the most jaw-dropping surveillance leaks, many people feel unencrypted and central-server service is bad in most of the cases, but end-to-end encryption can be used to reduce this problem.
Worldwide Government surveillance raises privacy concerns and acquisition of WhatsApp by Facebook also made us think about the security concern with chat applications
Source: TextSecure: End-to-End encrypted and Open Source Messaging app