Its not the playing in a party or a group I dont like. Its the mentality of most of the people in a random group and the waiting literally for hours for a party just to progress your character, (these can change if you join a LS/FC and get to know people). Like others have mentioned, Some of us have kids (I have 4), household duties to do, might have interruptions, and these things are "intolerable" in party play so its nice to be able to pop in when you have some downtime, Progress your character a little so you don't lag woefully behind, be able to duck out to deal with certain things, then spend your day off going hardcore with the rest of the LS.
I honestly must apologize that for myself, and those like me, I do want to be able to play solo for SOME things. I want the option to be able to pop on with rested exp, pound out a few levequests, gain a level then log off, knowing that I can just go do it. But I also want group things that we need to do to progress. There needs to be a balance. Video Games made it big because of the people who grew up in the 80's and 90's. 30 years later, many of us still enjoy games but lack the situations that allow us to sit there for hours on end every day.
My biggest beef with party play that i've experienced is for the most part other players would rather berate you then assist you. If you want to make more people desire the party aspect of a game you need to make it more appealing, but that onus is on the individual themselves. For every 10 nice players you run into there's still that one asshat talking shit that turns people off. Unfortunately there is no way to control that effectively, yet....
The tone of the OP says to me that people like me are not welcome. "Just go play offline and leave the MMO to the elite. We need a challenge and want to play with huge groups but only if you know what you are doing. We wont have these things if you insist on whining for the ability to play solo, even to a point. Solo players ruined this genre." This may be over exaggerating the actual OP but the sentiment is one i see expressed a lot when this topic is brought up.