I'd add that one doesn't need to be a high skilled player, but needs to know what the skills are, or the objectives are, even if you can't physically execute them well consistently in terms of evaluating good golf design. But I'd add to those that imply more outside skills and knowledge are needed to be a good critic. Those as mentioned, are knowing and experiencing a large sampling of various courses by various architects, and the historical aspect. And, I'd add that one would be even better equipped to evaluate course design with knowledge or keen observation of the process; from field routing, pencil and paper design on topo, and understanding the engineering and actual construction techniques. All of that goes into a higher quality evaluation or critique, IMHO.
So, the more you expose yourself to all aspect of the art and craft of GCA, including the actual construction, on top of the actual playing experiences and skill set, the better you should be as a critic.