I agree totally that umpiring is not an easy job and certainly mostly a thankless job. I also agree a coach should not let any situation reach the point where he should/would be ejected from a game. That being said a coach also has a responsibility to protect and "go to bat for his kids". A coach should have a right to question an umpire's call without an umpire ejecting him as long as he is civil.
I questioned an umpire's call on a strike this season when the ball was called a strike over the kids head with the game on the line. I merely asked the ump how could he call the pitch a strike and got threatened with an ejection. The kids can't question the call, they just go back to the dugout shaking their heads and feeling that it doesn't matter how good they are, just that the game was taken away from them. If a kid feels wronged and doesn't have someone willing to stick up for him this is just as bad an example as a coach being tossed. Every umpire should strive to get the call right..even if it means changing their initial ruling. Are umpires perfect, no few of us are. There will be mistakes, it is an extremely difficult job and thankfully they are willing to subject themselves to the abuse they do have to take. However, every coach should have the right to question a call but any coach crossing the line into lunacy should be suspended for a few games.