I may have remembered this incorrectly, but I seem to recall Maurice Ross discussing on the podcast some months ago how they try to set up the youth teams to mirror the senior side, so if we play with two wingers in the first team then we have a steady stream of wingers in the youth teams that will hopefully be able to transition seamlessly into the first team when they're ready. This dictates heavily the players that get retained and released each year, and I believe he may also have been bemoaning the lack of attacking/wide players that we had coming through. Again, I may have remembered that wrong.
On paper Robinson has some lower level first team experience, youth international experience, is an attacking player, relatively cheap, and was only available due to another club's financial situation (as someone already highlighted, similar to MacIver who hasn't turned out too bad so far). There's plenty other things in the world to be absolutely raging about right now than the signing of one youth player over another...