Iphone5 MMS: older phones not receiving messages

Question

Iphone5, iOS6.1.4, Verizon. Brand-new phone I bought a couple weeks ago. So its brand-new, mint condition, untouched.
I've been sending group messages, not realizing more than half of my friends/family were not receiving them.
1.My aunt lives on the other side of the country and has some kind of smartphone(not iphone) and she's been receiving them just fine.
2.My mother has a normal cellphone that is several years old AT&T, but she has only being receiving the subject line of the message. When she tries to "retrieve" the message, it always says "failed to retrieve". She has no problem getting text messages from everyone except me.
3.My brother has a different model of a normal phone and he is on the same AT&T plan with my mother and he is able to receive my group messages.
4.Some other friends with older phones and AT&T are not receiving the messages at all.
So it's been very hit 'n miss on who can receive these group messages.
I turned off iMessages first, then I finally turned off MMS Messages, and my mother was finally able to receive a group message from me.
She has always been able to receive an individual message from me with MMS and iMessages turned on. This is strictly a group message problem of some kind.
I was only sending her messages with text content, but the group messages always say MMS at the top regardless of what you send. I'm assuming turning off MMS forces group messages to use SMS.
Why is iphone not able to degrade gracefully with a group message? Why can't it detect older phones in a group message and say "hmm...maybe I should use SMS, especially since the iphone is sending a message with text-only content anyway."
It's really irritating that I have to either, remember to send INDIVIDUAL messages to every single person, OR keep MMS turned off just so older phones can receive a group message.
Has anyone else had these kinds of problems, and if so, what did you do?
Why does group messaging suck so bad on iphone? I group-messaged all the time on my normal cellphone and had no problems.
Even if iphone turned off MMS for a specific message-group automatically because ONE phone involved in the group was too old, that would be better than having to manually turn off MMS for the entire phone. Degrade gracefully, Iphone. It's a fact that older phones will be around for a long time still. My mother's generation still has 30-40 years left in them and they hate change.

Answer 1

Whether its the carrier or the phone model, why can't something detect that an MMS is the incorrect format?
Why send it as an MMS if one of the phones isn't going to be able to receive it? Why not use SMS automatically on the iphone when the messages are text-only content anyway? Don't force a group message to be MMS unless it contains content like pictures that make MMS necessary.
It reminds me of the time when I didn't have txtmsging at all and some friends did and they would send messages that I never received and they had no idea I didn't receive them. At least with email, you get a mailer-daemon shot at you.
I don't expect SMS to fire back a NDR to tell you that the receipient doesn't have txtmsging, but it would be nice if MMS would downgrade to SMS when needed. Or remain at SMS until MMS is absolutely necessary.
Why are group messages always magically MMS? The individual messages must either be automatically SMS or they are detecting what the phone on the other end can handle.