I agree BH, you can't look at things in isolation. But I think that it is questionable that we needed to make the move, and it is certainly questionable that it has produced a result. I don't think you can argue he has proved to be a better option then Cowan, Smith or Faulker would have been (or indeed Alaalatao's if he had stayed at LHP). I do think at this point in time that Robertson probably should be moved back to THP for his long term development and Australia & NSW look for other LH alternatives.
I don't agree with your last statement, unless that is their stronger side. I note It was reported Faulkner moved for that exact reason - his preference is LHP. LHP & THP are specialists in the modern game.
I have always assumed that the decision to pick Alaalatao & Robertson on their non preferred side allowed both to go back and be starting props at their super teams with a view that both would get more game time & develop.
In Alaalatao's case I think you can say it has been relatively successful. I am not convinced that it has still been the best thing for him, ACT or the Wallabies (Brumbies already had a number of Super level THPs - but I note one of them was Alexander who they could comfortably switch back) but it has been reasonably successful, so I'll credit that as a win.
In Robertson's case I think they have just weakened one spot to strengthen another. Reserve props play a very important role in the modern game. And they still get plenty of game time & plenty of development opportunity. They will often start as part of the season's player management system.
It seems to me that Robertson has regressed since he was switched. Instead of providing valuable back up at THP for the Tahs and developing into the future cornerstone of their pack, he is a make shift option. Not a bad one mind you, but he definitely isn't showing the potential he was when he started. Would it have been hard to find an alternate LHP. Possibly. But then finding a reliable back up THP at the Tahs hasn't been beer and skittles either. This puts a lot of pressure on Kepu.
As always, everything is easier in hindsight. i don't think Robertson is going as badly as some comments suggest. But he's certainly not showing anything to say he is more than a gap filler at this stage.
Maybe in 12 months I'll be proven wrong. I guess we'll see.