Dictionaries are in alphabetical order so it is a lot easier to find words. It is not as complicated, say you were trying to find the word ' that ' .You would take so long to find the word if it was not in alphabetical order. It could be on any page like 117. You just need to find the first letter of the word that you are looking for and then the word will be there.
Dictionaries can be very useful by finding the correct spelling and the definition of the word that you are searching for.If dictionaries were not in alphabetical order it would be so unhelpful for us.If it was not for dictionaries in alphabetical order i would still be looking for the word 'that' right this second.
Dictionaries are in alphabetical order because it makes it faster for you to locate a word and the definition of the word