Right, I'm familiar with the current rules and that they don't do very much to curb the problem of concussions or bad (read dangerous) technique. I'm not convinced that the tactical penalties need to change - they're severe enough. What I think needs to happen is that everyone, both players and referees, need to be held more accountable for their actions on the field than they currently are.
That said, though, I'm still not convinced that forcing a team to play with a 10-man team is even workable given the rules of American football, or even desirable.
For instance, would you propose that both offense and defense play with one fewer man for the rest of the game in a "send-off" scenario? What about special teams? If you used a "power-play" rule like ice hockey does, how does clock management (a huge part of American football strategy) interact with that rule?
Even if you could iron all this out, there's still the fact (which you acknowledged above) that a team playing with 10 players is extremely likely to lose to a team playing with 11. Couple this with the fact that referees are far from infallible (and are currently not held accountable for bad calls in any serious or transparent way), and you've got a case where one bad call early on could literally cost a team a game. To the best of my knowledge, personal fouls aren't contestable, and you can't appeal for a game to be replayed. This would be a huge problem even if you could iron out all the other problems with forcing a team to play undermanned. That's why I don't support that plan. Ejecting a player is fine, but not allowing substitutions is overboard given the nature of American football.