There seems to be a lot of confusion about what MMORPGs are. For what its worth the "G" in that acronym stands for "Game" and not "Group". The word group does not appear anywhere.
Playing an MMO solo is a perfectly acceptable playstyle and as the saying goes - "its your $/£/€ anyway".
Some people, myself included, like the environment they provide with a player-driven economy and people to interact with. At the same time grouping is an optional activity. Thank god that Rift (and WoW before it) no longer require you to find a group before you can accomplish anything. This frees me to go hunting artefacts or climbing mountains or whatever I feel like doing.
However - and its a big however -
that this means I'm not going to see group or raid content unless I join those structures. I will not get the rewards etc unless I subscribe to the mechanisms that provide them. I've done my share of raiding and I know the effort and discipline that is required to achieve results.
When a game starts providing the same or similar rewards for totally different levels of input then it is going bad. If the solo player is required to devote a similar amount of effort - eg over a longer period - rep grinding etc to get a reward then maybe that is balanced.
What no game can afford to do is recognise that people are soloing to top level and getting bored, perhaps even cancelling subs, and start panicky giveaways whose end result is to disenchant the people who have put in the effort. Those people, by virtue of being far more a part of the community than a solo player, are what hold a game together.