I honestly think that Texas tried to limit the amount of "targeting" ejections by having the shoulder pads be the first point of contact by the DBs. While correct in a static environment (meaning we're standing there and you get to pick your point), a ball carrier will almost certainly be trying to avoid the hit - leading to the main point of contact almost certainly further outside the shoulder (leading to largely a missed tackle) or closer to the head and neck (leading to a likely stinger or collarbone injury).
I'm adamant that football has to get the head hits out of it. The insurance companies won't let it continue if they're not eliminated. However, with current football alignments, we're going to develop a physics problem.
With 11 defenders on 11 attackers, it just isn't possible to play everybody 1 on 1. QBs are too adept at hitting receivers in stride. If a DB lines up inside, the ball is thrown outside, and vice versa. In order to defend (considering the defensive pass interference rules), you're going to have to have the threat of bracket (2 on 1 under and over the top) coverage. This means that there's always going to need to be the threat of a safety or LB running full speed opposite in direction to a receiver also running full speed.
Obviously, you can understand this without force vector diagrams. There's always going to be full force collision. It's no good telling the defender to break down and tackle. He's going to get a 230lb mass going 20mph right in his chest. Similarly, trying to arm tackle at those speeds just doubles the problem.
The ability to rapidly advance the ball in large chunks through precision passing and route running is too good to ignore. Football has moved away from the low speed pushing and shoving matches to a game inviting high speed collisions of human beings. The only solutions I can think of involve radically altering the structure of the game to make passing less attractive.