Though that practically differs little from the present situation, where holders of flexible tickets can make one reservation, but are at liberty to, and often do, ignore it. Particularly as I'd think only some people would take advantage of your proposal, particularly if it were (as it should be, to avoid misuse) for a fee per reservation.
In practice a reservation sort of means "don't sit here unless there are no other seats, and if there are you might have to move, but probably not".
Neil
That is how the reservation system currently works, but my argument is that it isn't how it
should work and neither is it how it is designed to work.
There are flaws in the reservation system in that people paying the cheapest prices (Advance Fares) must have reservations, whilst those who don't can optionally have them. However as the option to reserve is poorly publicised, and the reservation system doesn't work as it should (because of various factors including the fact that people don't sit in their reserved seats, don't travel when they have a reservation, or just don't know they can reserve) reservations aren't really effective and the whole system doesn't really work.
The thread is going somewhat off topic if I continue to argue my point on that subject - but the original point was that by allowing people to reserve their chosen seat, instead of giving people seats they don't really want to sit in, people are more likely to use their reservations and so social enforcement of the rules becomes greater. Similarly, that also makes formal enforcement of seat reservations easier. Better enforcement of the rules makes for a more effective system, which means people with flexible tickets might actually be inclined to book a seat. Building on that, offering new products to people on flexible tickets would most likely further increase the effectiveness of the scheme by implementing fairly simple procedures/rules and utilising available technology.
Just because something appears to work alright doesn't mean it can't be made to work better!