Potential is Potential, not the player's current ability level. Very few of those players in the NBA who you are calling announcers or benchwarmers would be announcer or benchwarmer in terms of potential. Certainly none would have been when they entered the NBA. Many NBA players, perhaps the majority of them, never reach the potential that was associated with them when they were drafted. The difference is that in real life, we either quickly stop paying attention to what a player's potential was, or we reevaluate what the player's potential is. In BB, the original potential is always what is displayed.
I think the problem is more with the BB users than it is with BB. Most people don't seem to take in to account that Hall of Fame potential on a 28 year old who still has a salary under $25,000, for example, really doesn't mean much at all.