Various posts elsewhere have pretty much identified that HTC and Nokia were told by VZW that they should turn off the option at the firmware level but nobody seems to want to confess as to why that was done. "Rooms" was one unacceptable answer which clearly has a related purpose in life but not for the ad hoc group texts that show up all the time. MMS APN *could* work but I asked that directly in another post and was given the party line of (paraphrasing) "use Rooms" and "don't expect it to work like your iPhone".
Bottom line, they screwed up and can easily fix it with a firmware update pretty quickly and hopefully will unless they are preparing to unveil the master plan as to what will replace this functionality. I think someone just checked the wrong boxes and hosed everyone and now they are afraid to turn it back on because "there must have been a good reason at the time".
And since my iPhone (still waiting on my HTC 8x to show) can group text with Verizon Windows Phone 7.5 phones and Android Phones without any problem there's zero good reason for WP8 to have this turned off. Since I know it's out there and probably will get fixed it's not enough to make me return the phone (the one I don't have yet) but for some it's easily enough to have them either choose Android/iPhone or if they have an easy carrier choice to pick WP8 on AT&T.
