Solution: don't use it with plain text, but with compressed files such as photos and movies which have high entropy by virtue of their compression (if it is effective, that is).
Looks like you're getting the hang of it: good steganography relies on having better statistical models than the opposition.
Things are weighted in favour of the concealer, however, as (unlike the attacker) he doesn't have to worry about false positives/negatives
Furthermore, hiding even an unencrypted message still adds entropy, since you're encoding more information in the same amount of space.