Because at the end of next year we'll likely be seeing the end of Viney, May and Max so you need to keep the list moving rather than be short sighted and throw hail Mary's for the sake of 1 year.
It's not 2009 mate, we're looking to actually develop players, all those ones you listed would have debuted round 1 after their draft and be considered dud picks by now if it was up to you.
I reckon Max might go on for a while, but agree those three could easily be done as early as next year (Barring serious injuries).