Whether you think her method of the break up was acceptable or not, she decided to end things with you in a way she felt comfortable to do so. It may not seem fair, and it may not be the way you would handle things, but what's done is done. Like you said in your post, "we're in the year 2016 and things have changed in terms of what's acceptable in the dating world. A lot of people text as their primary form of contact in general".
I personally think it depends on the situation and the level of commitment you agreed to. I do agree it's pretty callous and cowardly to break up via text; but not everyone thinks about it the same way. A lot of people lack capability to be vulnerable in front of other people, and having conversations like a break up, or "where is this going?" can be difficult for people to articulate in person. So in order to absolve themselves of the discomfort of a difficult conversation, they hide behind technology. When you don't have to see the face of the person you are hurting, it's much easier to do it. I am not saying that it's cool, or that it's a favorable way to handle things, I'm just saying that a lot of people seem to prefer that approach nowadays.
I hope you can pick yourself up and move forward from this with a positive mindset. It sucks to get dumped, especially via text/email/social media; but you are better off for it in the long run and it leaves your door open for another amazing person to show up.
"Caring is not an advantage."