1) A very broad, significant swath of your player base wants group content, namely in the form of Instances/Raids, with some love given to PvMP. Also, skirmishes and open landscape group content (think Limlight Gorge, the eastern half of Angmar, etc.) have been mentioned to a lesser extent. The MM in MMO is there for a reason: people play these games to have content to tackle with other players. We know the numbers cited by members of the Turbine staff, in regards to the percentage of players that engage in these activities, but any educated person in math/statistics/science knows that without transparency of data and defining your terms (what constitutes a group/instance player? as already noted by several posters, among other questions), the numbers mean nothing and can be interpreted in various ways. Also of note, is that those players that enjoy group content are often kinship leaders/officers, and it's their contribution to the game that keeps many other players coming back. Their absence is being sorely felt by many servers as we speak...which brings us to-
2) There's a reason Helm's Deep didn't do well compared to past expansions. There's a reason Big Battles weren't well received and are not widely seen as a viable replacement endgame. There's a reason the population has dipped frighteningly low and kinships are dissolving left and right. If this thread is to serve any purpose, it must be seen by the decision makers of the game. All this feedback will have no purpose whatsoever if it isn't acted upon. Again, as I mentioned in a previous post, acting on this very actionable feedback (and actionable feedback is what Turbine is always asking for) may be inconvenient in the short term, but for the long term viability of the game it's very necessary. Pleasing your customers is just very basic, common business sense.
3) Like many others, I commend the Turbine development team for trying new, innovative mechanics (skirmishes, LI's, mounted combat, and yes, even Big Battles) but these should never be implemented to the exclusion of tried and true content (see number 1). This can in effect be tangential to number 2: There's a reason SoA, MoM, and SoM are looked back on with such fondness by many players. We got new mechanics PLUS additions to the tried and true group content.
In closing: I, like many others, have become very invested in this thread (perhaps too much?). Mal, thank you for starting this thread and giving the player base a venue to share their opinions. But, again, all this feedback is only worth something if it's acted upon. All of us--even the disillusioned, disappointed custumers--enjoy, or used to enjoy, this game, and would like nothing more than for it to return to its former level of high quality. Anyways, I'm just repeating what many others, as well as myself have already stated. I'll be eagerly awaiting the Turbine team's response.