sdayman's point is a very significant one to consider. If you're a savvy programmer you can figure out a way to script the process of creating email accounts, but you still need to be cognizant of Dreamhost's TOS.
Just poke around the forums and you'll see horror stories of people who have had their accounts suspended because their paying clients sent a promotional email to opt-in users. I know it sounds absurd and I initially questioned it myself, but multiple people have made this same claim.
It might make some people feel as if it's an unjust act, but that won't change the state of affairs. The account you're doing business with, for an exceedingly low cost, might no longer be yours. I've never heard of any sort of enforceable legal rights being violated by these actions, so you're likely to be out in the cold regardless of any potential outrage.
It would be wise to exercise discretion when doing anything that is frowned upon by the TOS.