As opposed to reshaping the round hole (ourselves) into a square hole for Aikido to fit.
I think that most folks believe that training is about reshaping ourselves. It's still question of the shape of Aikido is we might be trying to match.
Folks start training with all sorts of ideas about what the art is... after substantial time in, they should have a different idea (better informed) of what it really is. The ones who always thought it was about fighting almost inevitably start doing more and more cross training because they can't make Aikido work as a fighting system. Eventually, if they are really serious about fighting, they leave to do something that really is a fighting system.
The ones who never thought it was about fighting at all are usually far happier with the art and often have no interest in cross training nor do they spend any time at all on the net arguing about whether the art works "on the street". The big problem with these folks is that they use the fact that it isn't about fighting as an excuse not to look deeply into the principles which govern what we do. We are not talking here about people who can't use the art "on the street" or defeat a challenge from a practitioner of another style, we are talking about folks who cannot do their technique within the Aikido paradigm itself. This isn't about throwing the "un-throwable" man of Dan's description, this is about being able to throw an Aikido trained uke who has some intention and the ability to attack in a balanced fashion simply using the highly stylized attacks of the art. We are talking about people who cannot execute an irimi when given a standard shomen uchi with some intent to strike.
Stating that Aikido is not about fighting, which I do not believe it is, or was supposed to be, is a total cop out unless you have some idea what it really is. O-Sensei believed that Aikido was a budo that "completed" all budo. It is an art which should bring one to an understanding of ai-uchi (mutual destruction) and ai-nuke (mutual preservation) as described in the interview with Chiba Sensei which appears on Aikido Journal Chiba Sensei Interview
Aikido is supposed to be transformative but most people simply adapt their practice to their own comfort levels and stay the same. So, while they may be perfectly correct (in my mind) that Aikido isn't about fighting, they may have only the foggiest notion of what it really is or could be with real effort and good instruction.
If we suppose that effective fighting is indeed represented by the square hole and transformative spiritual practice might be symbolized by the round peg, as described before, most Aikido isn't either.
So we can't just say that we shape ourselves to the art because there is very little agreement as to what the art is.