It's possible to direct trains to the near/middle/far end of a platform. But how can this be practically used? I thought I could use this for one-way stations, so that long loading trains would stay at the far end and quick unloading trains at the near end, but for this I would have to separate them by signals, which doesn't seem possible.
Trains decelerate as they enter a station. If you have a really short train using a long platform, it can take longer to arrive if using a "far end" order, as the train has to decelerate over the length of the platform. By setting the order to "near end", the train only has to decelerate over the length of the train rather than the platform, which can be an important time saver.
It can also be used for cosmetic effect, for example making a short train stop in the middle of a long platform rather than far away from where the passengers would be waiting.
Unfortunately, it's not possible to have multiple trains share the same platform using the near/middle/far options. It would certainly be a useful feature though!
The "far end" option does have a single use.
In a situation like this, where the station is the pickup, but not the drop-off for a route, it's better to order a shorter train (maybe trains don't yet have enough power to use longer trains, or you can't afford one yet) to stop at the end of the platform, so it takes a shorter time to get to the other side of the line, which will earn you more money.
Though switching the signals would help even more in my particular example, but that's beside the point.