Ports have been made available for computer users so that they can add external devices that can enhance their use of a PC such as storage or communication devices. With the provision of several USB ports while the other ports not available in the same number, the need for more serial ports have been recognized and thus one can purchase a docking station so that they can get a number of serial, parallel, PS/2, Ethernet ports and so on and so forth.
All one has to do is plug the USB jack into any of the USB ports and then use whichever port that is required for the external device. At another level altogether, with the obvious lack of serial ports as compared to the USB ports available, another device known as the USB serial adapter can be used to connect all your devices that requires serial ports.
Apart from these devices that deal with communication (modems, digital cameras and printers) and storage (external hard disks), one can also use a USB audio adapter to either use a mike, headphones or even a surround sound system.
Strangely enough, with all these devices available for users to take full advantage of the numerous USB ports, there will be no necessity for computer manufacturers to add any more serial or any other kind of ports.