In general, no lubricant last forever. So a regular change is a good idea, regardless of manufacturer recommendation. As mentioned, you can only change a fraction of the fluid by draining the pan.
Some transmissions have external cooler and a full transfusion of fluid can be done using those lines, but this is usually not an official procedure. Some sensible manufacturer recommends transmission pan drain and refill say every 30K. That way, the transmission will get some new fluid regularly and the fluid quality won't degrade to an unacceptable level.
For those DIY people who take a long term view, my gut feel is that a pan drain and refill every second service beginning from say 45K is a reasonable approach. Waiting for problems to come up before changing is not ideal as wear / damage most probably have taken place.