The reason I find it absolutely crazy is that you can't stop people from sending you messages. You can blacklist them (or use a whitelist) of course, but that's still "after" the offense. What happens if a millionaire prankster sends you 20 messages some day? You have t cough up something because of his prank? I find it unreasonable.
But I don't find paying more for calling a cellphone objectionable. A wireless call requires more resources and money for telco company than a wired one (they put wires in houses decades ago and have forgot about it (the maintenance cost is not huge), but they have to actively setup new towers for different locations in cities and change the old ones). It costs them more, so they charge more and I pay more.