See, I hear this a lot and its totally bunk. The POP flagging system was accessible toEVERYONE, but it wasn't handed over on a silver platter, yes,you did have to work for it. Effort was required. The game was what, four years old, and the majority of the player base was 65, so it only made sense to make an expansion that catered to the higher level players. The POJ trials were a frikkin breeze and actually required very little effort as they had groups running people through 12 hours a day. Not just guild groups, just whoever was there. I was in an upper tier guild but didn't even need to group with guild mates because another guild was just running anyone who showed up through a cue, so I put in my name and an hour later they jammed me in with a bunch of total strangers and we breezed through it. I actually got a few lower tier flags (Disease, Nightmare, Storms, Torment) just running through with pick up groups because I was working a lot of nights and missed a few guild raids.
My point is, if you tried, you could conceivably join pick up raids for all but Time, and later in the expansion, there were even pick up raids in Time. It was possible if you tried, and those who didn't and just complained, well honestly, the flagging system was great because it filtered out the crap, immature, annoying players, so if you zoned into say, POF, the only groups there were serious, dedicated players and the game became ten times more enjoyable as you didn't have to deal with garbage players, KS'ing, that idiot who will run in circles around the group jumping every 10 feet while waiting for pulls, arguing in OOC or SHOUT, none of the usual crap one has to put up with in the "open" zones.
Besides, the "casuals" were not even capable of grouping in the higher level Luclin zones, most casuals were still hanging in Chardok, KC, and Sebilis. They are called casuals for a reason.