Looks like the round-trip orientation is also messing up booking for award RTs, though in that case it appears more straightforward if you just book two one-ways.
They've gotten zero bookings from me since starting this and I still haven't found anything positive about it from the customer perspective.
Heck, it could be the Internet equivalent of the old, old practice of airlines NOT quoting the lowest fare over the phone and seeing if people will still buy it.
Maybe the hope is that mentally people have a figure in their head and the goal is to get as close to 100% of that as possible.
OTOH, that'd mostly apply to new customers, not those with a good idea of what to try to aim for based on time-of-year and history.