second, the queen does make decisions... the most important ones starting by nominating the prime minister she is also the cheif of the commonwealth were she is not only queen of the Uk but queen of Australia and new zealand and all the commonwealth countries. And yes she has a ****load of decisions to make , she is the head of state.
third, think of this like Obama was your king and Sasha was getting married, she will eventually be the queen and the head of the united states and that alone makes it a big deal. William is in the direct line of the throne he will be king, that is why this was so big and it wasn't even a marriage like charles and Diana cause he is not the next in line.
Dont expect this kind of wedding with this magnitude for all the royal family members, their importance in the linage maked it what it is.