By default, email messages are sent in cleartext over the Internet. A common analogy is that an email is like a postcard - anyone who handles it along the way from sender to recipient can read the entire message. In comparison, encrypting your messages is like putting them in an envelope. But here the analogy suffers, because the digital envelope of encryption is so strong that, as far as we know, even the NSA can not force it open.
For this reason, strong encryption is a threat to government power and it is very likely that governments will sooner or later try to prohibit it. They will not outright ban the use of encryption, but rather require that people who use encryption provide their decryption keys when asked by the government. This is already the case in several jurisdictions.
When we come to this particular point in the expansion of tyrannical power, developments might turn on the number of people who have adopted encryption as a daily routine. If encryption is still a fringe phenomenon, there will not be enough voices to avert government abuse. On the other hand, it is possible that if a large enough segment of a population is using encryption, it might be difficult for politicians to push an anti-encryption agenda. In any case, if millions of people are habitually sending encrypted messages, it will be much more difficult to target them systematically.
So even if you currently are not concerned about your personal privacy (although you definitely should be), you should still use encryption and encourage others to use it. If many of us do, it might provide a bulwark against state suppression of private communication. In any case, it will strengthen the capacity of the general population to resist further power-grabs by the cleptocratic elites.