So what do these security changes mean for the spotter wanting to causally walk around the piers which has always been a nice way to kill a few hours interlining at AMS?

If the same setup will be used as already in use at the Schengen-piers, then at least it will remain the same but probably a bit easier still as there will presumably no longer be individual areas per gate for screening purposes. Although I would suspect flights with a higher risk for terrorism (e.g. El Al) or drug trafficking (e.g. Surinam Airways) will keep special treatment.