When an iOS user texts with a android user we lose all our nifty Messages featurea. I’m sort of convinced this is not completely unintentional on Apple's part (or at least, they would never do anything to make it otherwise ) because even though I completely understand that this has nothing to do with the android user I find myself getting annoyed that they "took" all my cool iMessage stuff.
The color itself isn't the thing really. It's what the color represents: all of the features that iMessage provides don't work with SMS. Instead of little icon reactions, there are long messages ("pwinnski liked 'Okay, see you there'"), location-sharing is ugly, URL-previews are wonky, etc, etc.
It's a diminished experience because SMS is a terrible protocol, the color just lets us know what to expect.