The idea, I imagine they believe, is that when you have to go to suffficient lengths to keep your data confidential, you will actually draw even *more* attention in the process, and even if you are not guilty of anything in particular, may find yourself more heavily scrutinized by the powers that be than the average individual.
The use of strong encryption in no way implies that you are "guilty" of anything or have "done something wrong."
It means you have taken proper and necessary steps to secure your data against unauthorized access. That is what all good digital citizens should be doing. Many don't, and that's why we see stories every week about a large data breach of names, addresses, social security numbers, etc. being handed over to criminals.
Since everyone is subject to suspicionless, unwarranted surveillance, it doesn't seem to me to be useful to be concerned about drawing even "more" attention to yourself. You're already under surveillance, by doing nothing at all. That's why we use of encryption.