I have a feeling that all of you folks are near the ocean. I am not. The Great Lakes are big, though. I went on my first solo kayak trip the other w/e (3 day). I don't know any other 50 year olds that want to paddle as hard as I do and eat as poorly. I am sure that there are many... just that I don't know them. I am a crappy outdoors cook in spite of canoeing all of my life... including solo.
I was a canoe instructor at 21 and can still empty a canoe in less than 2 minutes after dumping alone in deep water, but the kayak is somehow different. You have much greater ability to save yourself, but I think that it is much easier to dump. This statement is reasonable only when you consider reasonable water conditions for each.
I may also feel this way because I am much, much more comfortable in a canoe than a kayak (I do have a solid roll and try my best to always edge high with drama and flair!) Not withstanding this, I think that it is all about judgement and preparation.... the safety gear (practiced with) and the skills. I also believe that we have to be honest with ourselves and consider whether we have got the chops for a screw-up on the trip that we are planning. Have we screwed up before (in any area of our lives) and how did we handle it. Are we cool and logical, or do we tend to panic a bit? This is a tough question to ask of one's self, but necessary. I find that so many people today have been bitten by the "extreme" bug, that they can't just enjoy their sport. Each outing must be bigger, harder, edgier! The problem is that skills take time.... years. And real comfort in a kayak has to do with time in.
This is a bit of a ramble and I am sorry for that. I think that soloing is fine. It is most of what I do because I can't wait for others to schedule time. I just think that we should be prepared... physically, psychologically, equipment wise and actually have "the chops" to take on what we are doing... and to recognize the real risks and consequences of our planned escape. Then go for it!