IR is just a communication channel. It depends on the functionality of the channel if it supports one or two way communication. With IR you can never (ok, not really never, its just hard) achieve full duplex communication, but dual simplex can be achieved easily, you just need some hardware and software, which most devices lack, or better they were never designed to offer two way comm between the device and remote, because there was simply no such need, and it added extra cost.

This is why rs-232 is so much used today, and why IP is entering everywhere. Although if you want deterministic and true rock solid comm. go for the rs-232 and avoid using IP in big/busy networks. I don't see IP as a replacement to rs-232, it's just another way of communication.