It's Kind of Cheesy Being Green
medium.com
medium.com
However, if you have an iPhone and don't like the green bubbles, you become a sort of brand ambassador -- you'll both have a greater chance of staying on iPhone (because you associate the "green bubbles" of other phones with being inferior, you won't want to get an inferior phone), and you'll also try to convince your friends to get an iPhone.
The images in the article seem to all be from immature young adults. Children will find the most petty, ridiculous things to differentiate themselves with, it's what they do.
e.g. 'gay' as a playground insult.
Also, what happens if a message is sent while data is disabled from an iPhone? Does it go through as an SMS and appear in green to the iRecipient?
Two big items are that it's designed to add group texting features in a way that makes non-iMessage clients not respond correctly (reply instead of reply all, but only sometimes) making users of competing standards seem rude in social situations. On top of that, it will lose your data if you unsubscribe (http://www.cnet.com/news/apple-must-go-to-court-over-disappe...)