Kaynight, I suppose it's possible that a pawn could reach the last rank before any pieces were captured, but I can't imagine it would happen in a real life game. However, just to cover all situations, another rule could be added saying that a pawn could not be moved to the last rank until a piece had been captured. In fact, this rule was used in the past (see the link at the end of this post).
And yes, I am serious about changing the rules, even though I am just a chess club hack. Here are some reasons why I believe this change would make chess a richer and more interesting game:
1. Having two or more queens on the board gives a player an overwhelming advantage that no opponent can withstand. Most likely, the game is pretty much over as soon as the extra queen appears.
2. The rule change would add a slight degree of tactical decision making. For example, do I push my pawn now even though my opponent has only captured a couple knights and a bishop, or do I focus on something else until my promoted pawn can be exchanged for a greater reward?
3. Chess has a theme, even if it is a highly abstracted one. Two armies are battling, each headed by a king along with his queen. Royal polygamy aside, we traditionally think of a king and a queen, not a king and his queens. Allowing extra queens on the board violates the theme of chess.
4. Also, consistent with this theme, we could think of a pawn sneaking into the enemy's fortification and freeing one of the captured pieces. But in doing so, the pawn is itself captured. It shouldn’t be possible for the pawn to free the queen if the queen is still on the board.
I know that some of you may laugh. Change the rules of chess? Never! But in fact, a restricted pawn promotion rule has been used in the past. See this link: https://en.wikipedia.org/wiki/Promotion_(chess)#History_of_the_rule
Now watch this absolutely brilliant game unfold:
Now, you're dead lost. How do you survive?
personally, it doesn't bother me. In blitz they can be useful, but as a player who rarely plays any quick games, I almost never use the extra queen. It really only comes into play when some poor sap who is already beaten refuses to resign and she serves to expediate the final mate.