I asked in Kin chat and a player who has already got to level 58 (time to empty that bucket Amfi ;)) surprised me by confirming that most of MoM is in fact soloable.
A defining feature of the early days of Lotro for me was the number of great quest chains which started with solo quests and ended in one or more tough group quests with high quality rewards. This pattern persisted through the Lone Lands, North Downs, Trollshaws and into the Misty Mountains. It fell apart a bit in Angmar because the quest chains were a mess originally but that eventually got sorted in the great Angmar Revamp. Even though some folks complained when the ran out of solo quests I loved that system. I found I could keep myself busy soloing the starter quests while keeping an eye on the LFF channel for someone doing a fellowship quest I was ready for. I had some great experiences pugging my way through the mid levels of Lotro this way. It trained folks into grouping and it did engender a co-operative spirit that I believe persists in Lotro to this day.
Of course things became more difficult as the bulk of the population moved on and it became harder to get a group to complete low level fellowship quests. I believe that Turbine subsequently revamped a lot of the lower level stuff to make it soloable in order to overcome this problem. That is understandable but I had hoped that the advent of MoM with everyone levelling up together again might allow them to re-establish the pattern of Quest chains leading to fellowship quests. Sadly it looks like Turbine decided not to do this favouring solo-able content instead.
On the positive side there is always the book quest line which has some great fellowship content and I hear interesting stories of some very enjoyable 3 man instances. There is no room for error in a 3 man group, so I am looking forward to some challenging fun.