I agree with you, IMHO there is currently no need to ban GPS watches.
But you could still use a GPS logger without display. I own a small QStarz BT-Q1300ST, gives accurate tracks if worn the right way (shoulder, upper arm, head band...).
It is a real pain not being able to analyze the big races that one is training for and trying to get a top result in. At the same time I can kind of see where the IOF are coming from. I've had this discussion before and we were able to come up with two things that GPS watches could potentially be useful for:
Distance estimation - You can easily get a reliable estimate of your distance from looking at your gps watch
Track view - This is where you can see, with no map, a track of your route. You can look at this to see how straight your line has been, or if you are veering off line on your compass bearing for example. This can reduce the time spent on mistakes.
The conclusion we had was that GPS watches probably wouldn't make you any faster if you are already doing everything right, but they could certainly reduce the time lost due to mistakes.
Another useful use of GPS watches in orienteering not mentioned above may be in returning to an earlier control in a butterfly or similar forking scheme (you can push the button of your watch the first time you're there and it will guide you back the next time(s)).
Generally, I agree with what was said earlier that the Pro's usually would not benefit from GPS watches; it is however a different situation for those less skilled in orienteering.
I think we also need to consider reputational issues: people not familiar with the speed and accuracy of our sport on a Pro level will simply not be able to understand why a GPS is not of big help in Orienteering. So I have some understanding for the IOF's position.
Finally, I agree that GPS loggers may be a solution for the problem described.
I'd change the rules in the following way:
WCup, JWOC, WOC: Forbidden to carry and use navigational aids
WRE: Forbidden to use navigational aids
I do have 3-4 different GPS-loggers without display, but there is always some trouble with using them (mainly because I use them quite seldom), e.g. software for transfer of data to the computer and so on. And because the others don't use GPS-loggers either, the incentive for me to bother with it is also not that big.
If the IOF want to enforce a rule that the athletes don't want then they should provide a solution.
Namely, make it mandatory for WREs to provide the athletes with GPS loggers or live tracking. On top of that the IOF needs to send WRE hosts the GPS loggers they would need for free (or at least only charge shipping) so the responsibility doesn't fall to the WRE hosts. If the hosts have to figure out where to get them and pay for them it just won't happen or nobody will host WREs.
Not only is it good for the athletes to provide that kind of service but it's good for the events and the sport to be able to refer to the tracks afterwards in news reports and for promotion.
Jan's suggestion is what we should have ended up long time ago if even a tiny bit commons sense been used at some point.
I do have 3-4 different GPS-loggers without display, but there is always some trouble with using them ...
That argument doest apply to Suunto's trackpod if you are suunto watch user. Very easy to use trackpod instead of watch if needed. Same usb cable, same download software, same training web log, same beep sounds for start/stop/split. Just more lightweight device to run with.