Toasts are great. There's nothing wrong with a good wedding toast; in fact, there are many things right with one that's apropos. A hilarious story from the best man or a poignant endorsement of the bride by the groom's mother -- these make for joyful tears and happy wedding memories.
That said, anyone not in the wedding party who feels it's his or her duty to make an impromptu toast needs to be tackled and carried out of the room. Guests are trying to enjoy their meals, singles are flirting and little kids are trying not to fall asleep. Nothing puts a damper on that like a confused, rambling speech from a distant uncle about how marriage reminds him of his collection of World War I memorabilia. Or worse (though more entertaining), a drunken ex-flame with a bone to pick.