It is so difficult to force stalemate and sometimes unintentional too, so why is stalemate a draw?
As the opponent doesn't have a further move, why is it not considered a win?
Stalemate is a draw in classical chess yet there are other chess variants both historical and modern where stalemate is not a draw.
Very early versions of Chess, such as Shatranj Chess (props to Andrew Latham) declare the player causing stalemate the winner and even today there are callings to return to that rule.
Larry Kaufman Chess Life Sept. 2009 writes:
"calling stalemate a draw is totally illogical, since it represents the ultimate zugzwang, where any move would get your king taken"
A typical counter to this point is that Chess tradition dictates that a stalemate cannot result in a win for the stalemating player because it would require a suicidal move from the stalemated player (moving your king into check is, in most forms of chess, an illegal move). If there are no moves on the board that you are able to make (other then resigning) then in making the stalemating move your opponent has effectively ended the game without a definitive result (capture of the king) and is judged to have not won the game.
So.. "In Classical Chess what is the probable origin of stalemate being considered a draw?"
The earliest reference I can find to Stalemate being a draw in formalised chess rules is 13th century Italy where the version of Chess played declared that a game could only be won by checkmate or resignation. Stalemate, under those terms, describes a state where a player cannot make a legal move. In effect the game has stalled in a state where neither player can achieve Checkmate and is drawn.
Stalemate as a draw then spread to Germany (1400s), Spain (1600s) and throughout Europe by 19th Century when the formal rules of what we know as classical chess were put in place.
England was one of the final adopters of Stalemate as a draw in the 1800s (up until that point the stalemated player had actually been declared the winner).
Yes tradition does favors the player in stalemate but it has been that way for a very long time. The flipping of that advantage to the stalemating player would greatly change the nature of the endgame (and thus the game of chess and a huge amount of chess theory), which is probably why such arguments have not recieved too much traction.
As Totero notes, changing stalemate in this fashion would drastically change endgame play. Currently, one must learn how to recognize different King/Pawn endings, and how other pieces interact with these endings. Opposite- vs same-color Bishops, Knight/Pawn vs Knight, Rook/Pawn vs Rook, and other basic variations.
Changing stalemate to a win would throw much of that out the window. Who cares whether White or Black has the opposition? Just run that Pawn down the board. Rook/Pawn vs Rook? No worries, just force a trade, and the win is guaranteed. It might not be fair to say that this would trivialize endgame play in reducing it to mindless exchanges from material superiority, but it would be a drastic change.
Put another way, it takes more skill to calculate and remember ending positions than it does to march one's way to a stalemate, and the stalemate rule is intended to recognize that fact.
I think stalemate is a draw for the same reason that dropping the white ball when potting black is a loss in 8-ball pool - it gives the losing player a granule of hope until the very end, and it ensures that the winner must be clinical in securing his win.
With regards to whether this flows logically from the other rules of the game - chess is, after all, a human made game, not a form of mathematics, so a rule does not have to be logically consistent with all other aspects of the game. If we all agree that a specific rule is good for the game, then we don't need to justify this rule against the logic of other rules (en passant and castling are similar).
I remember reading somewhere once which advocated that stalemate should be (could be) 3/4 point. Unfortunately, a quick google search turned up nothing.
The idea is interesting. It seems that you gained more by stalemating your opponent than you gain if the position is completely equal. By similar logic, the stalemated side seems to have not lost as badly as he would have if he had been checkmated.
There would definitely be some logic in considering Stalemate a win (after all, the opponent's King has to move and and will be captured on next move, so that should be a win).
However, this would have a huge impact on the whole Chess game. The reason is that, if Stalemate wins, now all King+pawn VS King endings are winning. Thus being one pawn ahead, exchanging all the pieces leads to a trivial win. I am not saying it would be bad, just that it would change the game more than you imagine.
For more details on the Stalemate (and on the key position in K+P VS K endings), you can have a look at the following blog post I wrote.
The objective of the game is to achieve a checkmate. If you leave your opponent no legal moves, then he/she is not in check, is not checkmated, yet can't move. It speaks to the ability of the player to recognize the possibility of stalemate, and avoid it while playing for the checkmate (or opponent resignation).
You haven't achieved the objective of the game, hence, a draw.
Stalemate is a draw by definition. Why is it a draw? Because this is the rule that was agreed upon in the 19th century. Before the 19th century, the stalemate rule was not standardized. By defining stalemate as a draw, winning has become more difficult. Stalemate is an important resource to hold a draw. For example, many rook endgames are drawn because the defending side sacrifices their rook to create a stalemate. The stalemate also offers escape from clearly lost positions where the opponent loses focus and allows the stalemate to happen. My view is that the stalemate adds flavor to chess.