> Is it a lack of knowledge from the users or do they really value iMessage integration that much?

My understanding is that the barrier to entry to using iMessage makes iMessage a LOT more secure from spam. If you want to do mass iMessages you have to register as a business with Apple, go through all sorts of checks and attestations, etc.

At any rate, iMessages are a lot more trustworthy than SMS. So being able to spam people via iMessage is very desirable. I recall a few months ago a guy posting his little spam-iMessage-as-a-Service product here on HN. You could build your little iMessage spam army using a bunch of Mac Minis...