Although this does not under any circumstance take away from the monstrosity of war crimes committed by Waffen-SS units, they (or the Germans in general) certainly were not the only ones to commit them.
Regarding D-Day for example, it is remarkable how some units never took any prisoners in the first days after the landings, as records and unit history show. This is well known in particular for paras, and while there might not have been any official "order", one can't deny some "systematic" approach there. Actually, if you go through the captions of the pictures in the review, "summary shootings" of SS-soldiers being taken prisoner are mentioned.
If you want to look into the issue, I recommend starting with wikipedia and elaborating from there.
IMHO, there is only one lesson to be taken from all of that: No matter how justified the intervention and how evil the opponent, war will always produce this kind of events on any side. War never has been and never will be clean.
As regards the 12th SS, either we agree to look at it from a military perspective and discuss its fighting force etc. (without negating any of the crimes), or stop our hobby.
The problem is not whether we focus on just the military aspects, but how much (undeserved) admiration we are willing to give to units known for their repeated crimes.