It happens quite a lot. You accidentally move a bunch of cards somewhere. Or you re-order a particularly important prioritised sheet list. Or you simply move cards around in a Kanban view not knowing your are destroying the priority of the cards.

The way for instance a Kanban board is oftentimes used, is to place the more important cards at the top of a column. If this becomes the standard way of prioritising cards (trust me, it will), then there's a strong need to protect that order.

A good way to combat these problems would be: hold down SHIFT (or some other key) while moving/dragging/re-ordering. Only then would re-ordering be possible. This could be a setting per collection, per board/backlog. A very good fail-safe. This solution is in place in TargetProcess (another management tool) and does the job beautifully well.

And yes, it's great that UNDO is available with ctrl/cmd+z, but oftentimes you haven't actually noticed what went wrong.