I think this is the crux of the issue with Velocity frequent flyer.
While Qantas may not be perfect, they do operate internationally so frequent flyer point holders have some sense of certainty of when and how to book reward seats (Generally, stay up till midnight to snap them up 1 year in advance).
Virgin do not fly internationally and rely on their partners for international reward seats, but there are so many limitations and niches when it comes to booking reward seats with their partner airlines that it takes away the value of being a velocity member.
Take for example the recent Etihad change where reward seats in premium cabins can only be booked 30 days in advance. Realistically, who would take such a gamble to wait till 30 days from a departure date to book an international rewards seat. Yes, Etihad 'set' this from their side, but from a Velocity member perspective, Virgin should do better and negotiate better terms.