Bluebird. The only changes I suggested are 1) enforce the current rule as it is written and 2) give the player receiving the ball Kick Catch Interference protection even if the ball has bounced more than once. In the current rule the KCI ends upon the second bounce.
Your question ending with a period "So, are you going to allow a kicking team player to defend himself when a receiving team player crosses into the neutral zone with every intention of taking him out of the play and out of the game." Some assumptions here but I believe I understand your point and agree it is valid.
Short answer: of course they can protect themselves and I have no desire to change that. However, I don't see how enforcing the rule and granting KCI protection to one player prevents the kicking team from defending themselves as the current rule only states the kicking team cannot initiate contact until the ball has gone 15 yards. So if the receiving team heads into the neutral zone that seems to indicate an initiating of contact. Maybe this is where clarification for officials would help, a definition for what constitutes "initiation of contact."
In the Robert Lee and Sterling City scenario Sterling City was initiating contact from the second onside kick on, my point being they didnt have a choice unless they wanted to stand and be hit before the ball has gone 15. This is not a issue at Robert Lee, this happens every week in multiple games and it seems injuries here could be reduced without degrading the nature of the game.