To have or to be
English does not tend to distinguish between enduring and transient states when it comes to matters of identity. I am ginger. I have always been ginger and, whilst it's possible I might one day be grey-haired or bald, the rest of my body will be decidedly ginger. Given the attitudes of wider society to us red-heads, my hair colour has become very much part of my sense of self. It's more than a mere hue, defines me far more than does my eye colour.
I am middle-aged. My sense of age is, sadly, also a part of my identity. I wish it wasn't, but that's a separate issue. Despite what some people might tell you, I wasn't always middle-aged. Once upon a time I was young! If I keep on drawing breath one day I will be old, maybe even ancient. To define someone by their age using the same language as when defining a constant feature of their person implies that age is somehow not a transient factor but an enduring and substantial one. In much the same way people are defined by other fluctuating traits and features, such as their weight or whatever job they currently hold down. The psychological impact of doing this may sometimes be positive but, quite frequently, can be decidedly negative.
Weight is a fairly obvious area where damage can occur. As a culture we don't much like overweight people, and have immensely lucrative trades all based around the regulation of weight. You are fat. Well, maybe you are dear reader, I have no idea, but let's say you are. If you are fat today, does that mean you were fat 5 years ago or will be in 5 years time. Maybe it does, but weight fluctuates all over the place and to define your identity ~ to say you ARE something ~ grant permanence to something that is really quite transitory. In this case it is identifying with a quality that society at large has a snotty attitude towards. Is it any better to identify with transient states which our culture approves of?
A person might be slim or beautiful today and derive considerable esteem from this, but there are no guarantees that such states will last. The prospect of one day loosing a prized quality could become a source of dread implying, as it does, not only a loss of status but also identity. If my whole sense of self is predicated upon my wealth and one day I am no longer rich, am I still me?
A small change in language might shift mental attitudes. A person who has beauty (rather than being beautiful) may be more conscious of how impermanent it is and so, perhaps, less frightened of the possibility of loosing it one day.
Of course, the question might well be asked as to what, if any, part of our identity is truly permanent over the course of a lifetime. We are constantly shifting, changing beings... though our sanity is heavily reliant on the perception (or illusion) that there is a central core of permanency.