To be honest, I do not know why Mathworks made this decision. Earlier both tcp server and client were Instrument Control only, but when they rewrote they made tcpclient() available to regular matlab. Considering that functions such as websave() and ftp() and restful services access is part of regular matlab it would not be defendable to say that tcp requires advanced functionality. But I don't understand why tcpserver requires a different toolbox.
The workaround is to look in file exchange for tcpudpip contribution which uses an external library.
