I guess it just feels weird. Dropping in photos and emojis to that sort of context has become too much a part of normal friendly communication now that I feel a bit hamstrung without it. Luckily Facebook Messenger is the almost universal workaround for now.
some people don't want to text, regardless if you're on an iphone or not. I've had people I just don't talk to much anymore because they only want to use iMessage and hate when it's the different color for someone out of the ecosystem.