Tim,
A good topic for discussion, so thanks for drawing my attention to it. I have myself wondered about this. However, nailing a person's nature down one way or another on the basis of a missing element can be a bit dodgy, as you need to consider many other things. For instance, how active/well-placed and strong the planets of that missing element might be in the chart. A chart always has some very intricate balance of energies or different energies at play, and such factors often do not immediately meet the eye, as we usually look for answers/aspects to specific queries. There are many ways that a native with a missing element in his chart might be compensated for its energies - say, if water were missing, but the person had an elevated/dignified/'aspectually-active' Moon, or even a well-networked Neptune, one of the angles in that element's signs (quite often the case), etc. On the other hand, a person without planets in water signs/houses might say that s/he has difficulties expressing his/her emotions. Yet, this does not automatically or solely have to do with missing planets in water signs. There too could be an active Saturn aspecting, say, the lights- esp the Moon, and inhibiting it from expressing its real nature.
Anyways, leaving aside all
dodgy but often-occuring configs, as some e.gs. even on this thread show; IMO, there is some truth to the subject of discussion here. People with an element missing or weak in their charts would consciously or unconsciously feel an inner urge to compensate for it, fill that lack, and to balance their lives and environments. Now, the difference between, say, gentleman X, with a lot of air and another, Y, with lack of air would be, IMO, that 'X' would naturally behave in an airy way, ie, he might be naturally gregarious, talkative, interested in intellectual pursuits, more-a-mind-than-a-heart person - all or most of which might constitute his nature, and this will come from the inside/this IS him. Y, on the other hand, might feel an internal coercion to compensate and make up for that lack of missing air
from the outside (adapt and adopt these energies), say, by working in a job that involves a lot of using the head, or by going for/attracting partners/friends that are airy. If he has a lot of water, he might try to balance this out through the opposite element of air or fire. So, Y might feel a yearning to get this air from the outside in order to feel complete on the inside. Now, silly me can't remember where I read a lovely comparison, in the light of the subject in question, of Marilyn Monroe's and Elvis Presley's charts. Whilst the former hardly had any earth and water, the latter was poorly off as far as far as personal planets in air and fire go (though Elvis did have a Sag Asc). Now, Elvis' fast, fiery and dynamic style of rock n' roll (through his music career) is well-known. Marilyn was known for her almost innate sex appeal; and, from what I had read some moons ago in that article, and can recall now was that she would often say that she longed for stability the most in her life.
Tim, to draw some sort of a parallel, this is something like your explanation on threads re an unaspected planet; a person with an unaspected Merc might blabber a lot, for instance
.
AQ7