The issue is with stagnation, people get bored of doing stuff on strat after a couple weeks, factions stagnate once they get control of land and defensive bonuses mean that they can easily hold territory against potential usurpers. Large clans have the ability to ensure that even with a small group of active strat players 'managing' a horde of troop producers they can effectively grind troops faster than their enemies can produce them. The defensive nature of the EU meta game and the mentality of of 'block membership' means that unless one side commits itself to a assive (and likely doomed) offensive the war is unlikely to heat up any time soon.
Stagnation:
EU has been locked in a cold war for over a month, before that there were daily battles and sieges. Since the fall of Yalen none of the 'big players' have done anything worthy of note (in all fairness the last few days coalition has launched an offensive, but the extent of that is as of yet unknown). There is no issue for any of these faction on mustering active players (check the numbers showing up for fights) nor having resources on strat (check my previous post on garrison numbers). It may be that that people have simply lost interest in strat, but if that was so would these people remain so obviously active on diplomacy. For example I see numerous Merc's posting here in the diplomacy and strat forum, although most of them claim to no longer be involved in strat. I also see members of every major faction posting in diplomacy threads so surely its not that these people aren't interested.
Overwhelming defensive advantage:
I am sure that the defensive advantage in this game is what is ruining it, even before siege equip was bugged defenders had it far too easy. As you cannot 'starve out' defenders nor do 'long term' damage to fortifications defensive advantage is overwhelming. Defences are (relatively speaking) historically accurate, they give the kind of advantage that defenders had at the time, but this is not balanced for game play and it leads to this stagnation. Attacking forces have to be SO overwhelming in numbers to stand a chance of taking control that launching offensives is strategic suicide. A new form of 'Siege' battle mode could be added which would allow for actual besieging of a fief causing MASSIVE attrition inside (this should require a much larger army and should after a number of days be successful, unless a reliving forces is sent).
Block membership:
Balance of powers on NA has proved that without dominating bloc meta games strat can be relatively fluid, unfortunately EU is so entrenched in its ways that it is unlikely to change. NA has undoubtedly seen a growth in 'block membership' over this iteration of strat, as is to be expected. However relations are more fluid in NA with powers rising and falling over time, this is very similar to strat 1.0. I can only speculate over whether the dominate powers of NA would retain their relations if there was a wipe, as EU faction have in the past. Ultimately the EU 'block membership' mentality is something which has not changed over 4 iterations of the game, since the formation of the 'UIF' the two major players of that faction have not once been in conflict, in response the other major powers have now aligned themselves along similar such lines, worsening this element of the meta-game. Maybe I'll find myself crusading in Nova Calradia, seems a lot more fun over there.
Conclusion:
Strat can be fun again if: 1.) Game breaking bugs (undiscussed) are fixed. 2.) Siege mechanics are reworked to strengthen attackers (e.g. 'Siege' battle modes) 3.) 'Block membership' mentalities are broken down and PLAYERS make the conscious choice to fight those who have traditionally been their allies.