I agree completely. For teams that run hurry up, I think changing the 1st down rule hurts them if they are playing fast and have to sit there and wait for the ref and linesmen to move up and mark the spot, allowing time to waste. Any chance I can get more football, I want that, so reducing the amount of time a game takes while reducing the number of plays doesn't seem like a fun solution for the fans. I also don't think we should make arbitrary rules for the last quarter or few minutes of each half. The 2-minute warning for the NFL is obnoxious and often interrupts the flow of a good drive.
As another commenter mentioned, I think an approach like soccer/futbol is the best option. We could have a designated tv timeout at the end of each quarter and obviously the half time ads, and the longer timeouts a team takes. But after every punt and touchdown, we don't need to spend 3-5 minutes watching ads. Teams should have 30-45 seconds to take the field after a change of possession. In that time announcers could do a quick 20 second promo for a company, even possibly displaying the logo on the field similar to the way they display first down line technology.
They could also use pop-up ads during the change of possession, that occur on the bottom or side of the screen. Announcers already do promos for many companies where their ads show up on the screen and the announcer will say this game is brought to you by "random corp". It takes little time and can give the teams enough time to gather their offense/defense for the change of possession.
Promotional boards similar to what they do in soccer are nice, but with all of the people on the sideline, they would be hard to see. Additionally, not every stadium has the boards like the 'shoe to have changing ads running at other parts of the stadium, and there's no guarantee those are visible on tv. It may be more plausible to have ads pop up on the screen during breaks in the action or on the field which can greatly reduce how long the games are while also satisfying the money hungry execs of the NCAA and NFL.