The Brees hit was an intentional forearm to the head and completely unnecessary.
The other 2 hits (Branch and Sanders), Reed lowered his head before contact. People are focusing on the person being hit, but they should really pay attention to the defender. If Reed keeps his head up and makes the exact same hit, he probably still gets a penalty on Branch (hard to avoid that unless you aim right or left of center) and doesn't get a flag on Sanders...and he would be playing this Sunday.
Kids are taught to see what they hit. I told my son before he started playing football that if I ever saw him make contact with his head down, it would be the last down he played. Helmets are for protection and are not weapons.
You want to fix this without fundamentally changing the game? Call unsportsmanlike conduct penalties against anyone (offense or defense) that is in motion with their head down. Start calling it in the preseason (those games are disasters anyway) and you will quickly see players adapt.
At the same time, eliminate the "helmet-to-helmet" call. If both players have their eyes up and their facemasks meet, no problem. You will still have the "blow to the head" call for guys who go high with their arms/shoulders, but I think the calls we all hate (like the bogus Fitz penalty a couple weeks ago) will be eliminated.