If you make no estimate what kind of hand your opponent has you can only reason in three ways:
a) you assume he always has the best hand. So you throw away your hand.
b) you assume he always has the worst hand. So you put your chips in.
c) you bet big if you have good cards, and you throw your cards away when your cards are lousy.
Clearly (a) and (b) are bad strategies.
The last strategy is not as bad as the other two, but still terrible. More often than not your cards are bad. So your opponent will figure out you're not willing to make large bets with lousy cards, so every time you don't bet, he will, and every time you bet, he won't. You're going to lose your chips that way. Basic game theory.
So you need to figure out what cards he could have been dealt so that his actions make sense. Then, from that range of plausible cards, figure out how often he has a better hand than you do. If you like your odds, you put your chips in. Otherwise, you throw your cards away.
It's a lot more complex than this, of course. But the point is that "estimating your opponent's hands", as difficult as it may be, is absolutely crucial if you want to win.
Finding what the best random function might be would be an interesting test of machine learning. But in the real world few players are going to do something like this so finding out what their approach is is going to be a better approach.
A beginner will primarily focus on what his own cards are. An intermediate will focus on what his opponent's cards are. A more advanced player will focus on what his opponent thinks his cards are and so on. The best players in the world are experts at figuring out which level you're thinking on so they can think one level beyond you.
Once you estimate your opponent's range based on his style, the cards, his previous actions, etc, you need to know what to do with that information. ALL IN Expert was designed to help with the second part.
It has immense value, in fact, it's the hardest part of the game. Figuring out what to do once you've estimated someone's hand is (with a little practice and the help of a good computer program) pretty easy.
The entire game is one big war to see who can estimate his opponents' hands the best, while preventing his opponents from doing the same to him.
EDIT: I realize that estimating your opponent's hands is important. Basic poker there. I'm talking about "estimating your opponent's hands" which is featured in one of the calculator's screens. That seems like an iffy thing to feed into a computer. It's a garbage-in-garbage-out situation.