SCTP requires more design within the application to get the best use of it. There are more options than TCP, the Sockets-like API came later, and it is young. However I think most people that take the time to understand it (and who know the shortcomings of TCP) appreciate it -- it is a well designed protocol that builds on our ~30 years of knowledge of TCP and UDP.

One of the aspects that requires some thought is that of streams. Streams provide (usually, I think you can turn it off) an order guarantee within them (much like a TCP connection) but there can be multiple streams per SCTP connection. If your application's data can be sent over multiple streams then you avoid head-of-line blocking where the receiver starves due to one mislaid packet. Effectively different conversations can be had over the same connection without impacting each other.

Another useful addition is that of multi-homing support -- one connection can be across multiple interfaces on both ends and it copes with failures. You can emulate this in TCP, but at the application layer.

Proper link heartbeating, which is the first thing any application using TCP for non-transient connections implements, is there for free.

My personal summary of SCTP is that it doesn't do anything you couldn't do another way (in TCP or UDP) with substantial application support. The thing it provides is the ability to not have to implement that code (badly) yourself.

FYI, SCTP is mandated as supported for Diameter (cf RADIUS next gen). see RFC 3588

Diameter clients MUST support either TCP or SCTP, while agents and servers MUST support both. Future versions of this specification MAY mandate that clients support SCTP.