I wouldn't say I remember phones, but I do have the capacity to remember who does/doesn't have an iOS device. I don't talk to everyone in my contact list daily.
I would say, everything that was added to messages in iOS 10 would be a benefit. Stickers, apps, one could say even the games. But it's takes someone to actually use the services to say they are good.
However, yes to the video question. Sending/receiving video through iMessage yields way better quality than through mms. That's proven knowledge.
1. I agree that all features could be stated to be added benefits. Even if you don't like something, someone else will. There is a market for everything. Literally, even cow **** will sale in the right market niche - as compost/fertilizer.
2. The knowledge that iMessage media transfers are better than MMS is as proven as the knowledge that Skype media transfers are better than MMS. It's a useless rhetorical fact.
That all goes out of the window when you're communicating with someone who doesn't have an iPhone or Apple device. People aren't going to buy an iPhone just so you can send them higher quality videos and feel good about your purchase decision, when they don't want an iPhone. They will buy what they want and deal with the detriments of that decision, confident that the benefits outweigh them.
And that's the problem, the value of the service depends completely on the existence of other contacts who can use the service, which are locked to one vendor's devices. This works well when you communicate with people who live in areas where Apple has high market penetration. It is worthless when communicating in areas where the vast majority of people do not own these device. The fact that you have one, and that it sends higher quality media to other iMessage users doesn't matter if you barely know any.