I mean, usually a passed pawn is a protected passed pawn, and if a piece attacks or blocks it, the opposing player can usually attack the piece, making the pawn passed again.
Passed Pawns

As someone who has been crushed by passed pawns many times, I can say they are a very powerful thing when used correctly.
A passed pawn can be used as a distraction. When you have a passed pawn that is advancing down the board, your opponent has to distract forces to deal with it.

@ EchecsRex
Yes, but if a rook is on passed pawn duty, and you generate play somewhere else, then your opponent is effectively playing a rook down!
In other words, passed pawns are often useful in distracting enemy pieces.
By comparison, your pieces that defend the passer, are free to move away at any time. And for advanced passed pawns, your defending pieces usually have more scope in any case.
However there are the situations where it's easily blockaded. A knight makes a good blockader because the pawn doesn't block its squares (like it would when a rook sits in front of it). If there is no other dynamism in the position, then a comfortably blockaded passed pawn is usually surrounded by the enemy and lost.
In certain middlegames, there can be an interesting debate. Is the passed pawn strong? Or can it be surrounded and capture? Can the side with the passer stir up play somewhere else? Or the defender's pieces too passive? etc.

A pass pawn on both sides of the board approaching the end game can be devestating; especially if they've traded down for the material advantage. In some instances I've found myself trying to defend both sides of the board with a king and some minor piece.
Since they have the pass pawn advantage any futile attempt to defend is normally pointless.
What is the point of having a passed pawn. Even though the oposing opponents pawns cannot stop it a rook, bishop, knight, king, or queen could. I do not see the point of a passed pawn? Please explain!