Being cheap and easy is not a problem, quite the contrary. That we as a society make this a good thing for spam is a problem, but I don't want to make the system shittier just because of the bad use of it.
My work email is virtually useless at this point due to the absurd quantities of spam I receive. I think the OP suggestions would actually make email less shitty.
Any communication medium that is cheap and easy will be relentlessly abused by spammers.
