Evolve or Devolve?

I've been noticing more and more spelling errors, the kind that spellcheck won't catch, but that still jar me. Popular misspellings generally involve homonyms such as bear/bare or steel/steal. I was unhappy recently to see someone who writes for a living use the word "canon" instead of "cannon." I'm not ready to get out the smelling salts and the fainting couch to bemoan the death of the English language, but I do think spelling, grammar, etc. are important. I wonder if less reading is involved in poor spelling, if people don't see words used correctly and therefore don't know correct spellings. That theory makes sense when I also see idiomatic phrases that people get completely wrong. You know the ones, like "It's a doggie dog world." In this case, people are hearing these phrases pronounced poorly, and never the see the difference elsewhere. Of course, I've heard spelling is being phased out of many curriculum, even in the lower grades. That can't help either.