The two most compelling reasons I found why strong encryption should be available to the public is the large amount of interceptable information spread daily via email and that individuals have enjoyed complete privacy for most of history.
The hundreds of millions of emails sent back in forth within the masses of the online public holds records of financial transactions, the passwords to private online accounts, and the registration for a variety of social sources that could be used against the individual if decrypted. Strong encryption should be allowed for the everyday regular person to send emails because the number of incriminating or illegal activity is relatively small compared to the large number of legal and regular every day communications that take place. The reasoning that encryption should not be allowed to the masses due to the fact criminals will use it is weak because without encryption criminals will still find a way to hide their communications.
Never before has the government had the ability to access the personal information of their citizens. In a society with no encryption, the government would have full access to all digital conversations and habits of their users, thus ushering in a system of mass surveillance similar to that shown in George Orwell's 1984. I'm not saying that we are going to be like Winston and friends and be forced into submission by the Party, but by having a government that is capable of being all knowing of their citizens is scary. The freedom to speech is also awarded in our Bill of Rights as Americans and with the government being able to look into the way we talk and communicate online, that may lead people to not want to take full advantage of the internet.