Basia, I think "martial" is as much in the eye of the beholder as it is a defined word.
Perhaps there's just a different meaning in some Aikido (or martial arts in general) circles than the regular meaning in the wider world? I know sometimes that's the case with some words. Martial is an adjective relating to war and military... We don't have another handy adjective form of the word 'war' that I can think of, 'martial' (from the ancient god Mars, the god of war) is probably the most commonly used adjective form of 'war,' (after 'military' as an adjective). I have never seen the word used any other way in any source, any book, any conversation, any dictionary, etc, other than on this website. It's an adjective used to talk about war, soldiers, military, battle between groups, etc...
I suppose over time words do develop special definitions, though, especially within specific groups. And I guess they can be used in new metaphorical ways and stuff... It just seems like what people really mean is 'self-protection' or 'growth' or other things, in which case why not just say that instead of borrowing another word that doesn't really fit as well? But as I say, maybe there is actually an understood wider meaning of the word that I'm just not familiar with.
I don't think everything valuable about a martial art is actuallly _directly_ due to it's 'martialness', though... Which I thought was the point of this thread! Many things we do in our lives benefit us in much wider ways then you might see from a simple description of what we're doing.