The rules have made it so very difficult on the D.
So O's will in desperation, sometimes just throw it and HOPE that the ref calls PI. Teams are open about WRs working on trying to draw PIs in those situations. And all too often it works.

To give a team more than 15 yards in penalty on any one call changes the course of the game too much.

No more spot foul for PI. 15 yards. About the only variation on that would be that from the 15 yard line in, the ball can be advance by penalty no further than the 1 yard line. Enough of the "half the distance" rule.

In fact that's another rule that makes no sense. The offense can commit a penalty inside the 20 and be hit by the full penalty. A defense can commit a penalty inside the 20 and it can be no more than half the distance to the goal line. Why? Let's say the ball is on the 2 yard line and D goes off sides. The worst that can happen is that the ball is advance by 1 yard. If the O false starts from the same point, the ball is moved back to the 7 yard line.....enormous difference and it is not logical or fair.