Section 1: The issues
The main problem, as far as I know, is that the birth rate of new raid groups is very low. This is connected deeply to the bigger problem that it is very difficult to enter the raid scene if you do not have experience already, more so than the previous expansion. This compounded with fewer competent raid groups and hence stricter entry requirements, means that there is simultaneously a lack of qualified recruits and a lack of casual groups willing to work with newer/weaker players. Also, leading a raid group is hard work and if the work needed to be done exceeds the benefit one derives from it, the effort will cease. Right now entering the raid scene is very hard as the failure rate of a new group in the current tier raid is high.
Another central problem that have always plagued 25m groups since they introduced shared lockouts for 10/25 and equalized the loot, is that 25m guilds have to become a hardcore progression guild or cease to exist. That is, a 'casual' 25m guild is very hard to sustain since the effort is orders of magnitude greater than running equivalent 10m groups. This problem has now also creeped into running 10m groups: the existence of LFR and a variety of other casual-focused activities have dried up the pool of recruits who only intend to play at a relatively low level. So 10m groups face the same dilemma as 25m groups since Cataclysm... either become a very fast paced progression guild or dwindle and die.
Section 2: Some solutions
I think the best solution is to band together as a server and see what we can do, particularly efforts from the better progressed guilds in sharing their methods and resources. However, the real issue is that struggling groups make the effort to reach out to the community. One person recently asked me to see if my guild had extra bodies to join their raid, which is struggling. They also told me that their raid leader does not read the forums and do not want to use trade or any other venue to recruit. I do not believe this is a unique situation. It is hard enough to stay afloat while recruiting, it is even more difficult if you are not.
So for those groups that are struggling... try to reach out to similarly progressed groups and work out some mutually beneficial relationship. It's better to have one functioning raid with a roster of 14 than to have two dysfunctional groups of 7. Some of this might involve pride swallowing, but in the end it is worth it. For raid leaders that read this: I believe you owe it to those loyal followers of yours to try to make a raid that works, even if it means you are no longer in control. This is a hard thing to do but I believe worth trying.
So I invite everyone from the existing raiding community on CC to participate in the conversation and share their ideas on how to increase raiding participation on our server. It affects all of us, regardless of where we stand on realm progression. A healthy raiding population with a healthy pool of recruits at all levels is necessary for the long term survival of any raiding team.