On the contrary, I've found that lame noobs have far more problems forgetting to set their commander to hold fire and cloak and sit him in a puddle somewhere than they do accidentally wandering in to mine. In fact, one of the most common reasons it is so easy to beat noobs is that they often accidentally send their commander wandering off into the direction of my lines.The game should end when your last builder/factory is killed, not necessarily when your com dies. Otherwise a lame noob can still have a chance at winning.
On commander death = end, you can't play TA like a game of starcraft. You have to play it like chess, where EVERYTHING you do is directed towards either attacking the enemy king, or defending your own.