In this article, I will explore a highly philosophical model to attempt an answer.
TL;DR: Because it means changing how we see reality - and that's a price few are willing to pay!
Let's explore the model:
Yes, the main terms are German - because I realized that the English language uses the same term for "how we see the world" and "how we think the world is" - a distinction that clearly exists in the German language. Then again, I use the term "world model" - so let's float with English. Let's take a look at the model from right to left. I will just gloss over the deep concepts of these terms, because this is just a quick glance rather than a scientific essay.
RealityReality does not care for us - it's just us who are affected by it. The better we get at predicting how reality will respond to our interactions, the more we start to believe that we are "right" about reality - while essentially, it's just congruence between our world model and reality around us.
For example, a team might just do what they do - oftentimes, oblivious of their managers' thoughts and without regards to whether any manager is even around.
ImpressionsAs we observe or interact with reality, it affects us - what we feel, see, how we classify things, and what we would do next.
Our impressions are strongly filtered: First, we only receive a limited amount of impressions - essential information may exist outside our impressions. Second, we have a strong tendency to only receive those impressions we are looking for.
As a specific example: A traditional manager observes an agile team in action. The manager might get the impression that "this team is working laissez-faire" because nobody is checking on people, and might also get the impression that "this can't work" because there is no visible hierarchy in the team.
To change our ways, it's quite important to discuss the impressions we receive, in order to learn where we lack "the big picture" or we're over-emphasizing details.
World viewOur world view is the main filter of the impressions we receive. Every impression consistent with our world view will be forwarded into our conscious thinking, while impressions that are inconsistent with our world view will either be reinterpreted until they fit - or they will be discarded outright.
In this sense, our world view is the "eye" through which we obtain information. A narrow world view will imply that few impressions will go through unfiltered - while a broad world view will allow us to receive a lot more impressions.
Giving an example again, when an agile team decides to abolish progress reporting in favour of live product reviews, their manager must first be open to the idea that "working software is the (only relevant) measure of progress". As long as the manager's world view does not allow measuring progress in terms of production-ready software, they will discount both the benefits of interacting with users and the additional productivity obtained by not tracking work. Instead, their world view will make them see all the problems encountered by the team as caused by not following "a proper process".
The challenge with our world view is that it is strongly related to our world model (which is why in English, that would be the same term): what we see depends on what we can see. As long as our model does not permit us to process a different perception, our view will be limited to perceptions consistent with our model.
Genuine change, then, requires us to at least permit the possibility that our model is incomplete or even "wrong".
PerceptionAs the German word "perception" is also rendered, "taking as true", we can only take as true that which makes a true claim within our world model - i.e., only that which is both consistent with what we already call "true" and also within a spectrum of what we can classify to be "true".
Problems arise when we have already accepted false claims as "true" - we will discard or re-classify perceptions that are actually based on relevant impressions.
To take this out of the abstract realm, as long as we swallow the idea wholesale that "order is good, chaos is bad", we will never be able to appreciate the shaping and creating power of change - because change means that we change away from that which we consider "ordered" into something that, based on our current understanding, might be "chaos". Specifically, a self-organized team may not have a spokesperson or team leader at all. Such a team appears "totally chaotic" from the perspective of a manager who is used to corresponding only with team leads - and it will be very challenging to accept such a team as mature.
As long as we rely on an immutable world model, it's really difficult to see the benefits of conditions that don't git our model. Our perception of things that others consider "good" might be "bad", and we will classify situations accordingly.
World modelAt the core of everything we see and do is our own world model. As hinted above, our world model has already decided whether any impression we receive is "true", "possibly true" or "false". Our world model helps us determine whether reality as we perceive it is "good" or "bad" and what we should then do.
The more static our world model is, the more binary this classification will be - and the simpler we will make decisions. Or, in other terms, "confidence" and "certainty" depend on a rather static world model, while ideas such as "doubt" or "hestitation" are related to a shifting or shaken world model.
Let's talk about me in this example: A few years ago, I was certain that clear process definitions would solve all business problems. Today, I stand on the perspective that clear process definitions in a changing world are the cause of all business problems - we need to be flexible to deal with situations that haven't happened before (and that may never happen again).
"Agility" might have to shake up our world model - as long as we're striving for certainty, we apply perception filters and biases that make situationally right choices invisible and lead us off-track. At the same time, the price of adjusting and softening up our world model may be high: we may need to admit that that which we fought for, sacrificed for, stood for, are no longer valid.
And that's the difficulty with agility: before we can get the benefits of being agile, we ourselves need to adjust our world model to be ready being agile.