I sent a mass text to several friends yesterday, and their reaction suggests this remains a taboo.
I find that interesting, given that most of us use social networks and are therefore comfortable with mass messaging and communication. For example, if I posted the contents of the SMS in a Facebook update, several people would likely have responded and I might even have gained a few 'likes' from the process.
My friends' reaction suggests that SMS to a mobile phone is still regarded as a personal message - receiving one makes the person feel as good as receiving a letter from a friend did when pen and paper ruled. Taking that a step further, the ubiquity of modern mobile phones appears not to matter to the personal relationship people have with their devices.
That relationship was established around a decade ago, when research began to emerge revealing handsets were quickly becoming personal trusted devices. So, many people may have an iPhone or Samsung Galaxy device, but they still regard it as uniquely theirs.
As for the mass text, it's not something I do very often, and judging by my friends' reaction I won't be doing it again anytime soon.