Jusy "getting in the flow" is not the point of most meditation.
"[M]editation refers to a family of self-regulation practices that focus on training attention and awareness in order to bring mental processes under greater voluntary control and thereby foster general mental well-being and development and/or specific capacities such as calm, clarity, and concentration" Walsh & Shapiro (2006)
"[M]editation is used to describe practices that self-regulate the body and mind, thereby affecting mental events by engaging a specific attentional set.... regulation of attention is the central commonality across the many divergent methods" Cahn & Polich (2006)
The practice of 'coding in the zone' might as well achieve the same effect as traditional meditational practices and be called meditation on that ground. In fact, you are training the control of your attention with that practice.
A lot of meditation in western countries consists of people forcing themselves to sit and focus, then measuring the amount of time they sat as an accomplishment. It doesn't lead to any long term benefit though, and if really forced, it will actually have the opposite affect.
EDIT: Actually beneficial mediation is something else, and the Tibetan traditions flat out understand it better than anyone, period, they're the Caltech or MIT. Other traditions are ok, but they're not the same caliber.
Flow is the state where it is no longer a struggle to control your attention. What you are paying attention to can require a very active mind.
Mindfulness meditation involves practice at directing your attention, your focus is on meta-cognition. Your breath is often chosen because it requires no attention. It's boring. That makes it good practice at discarding all the other thoughts that come up and focusing your attention back where you want it to be.
Sure, meditation is a broad term but this is at the core of the vast majority of what's called meditation.
Some ideas involve meditation with a goal (considered attainable or just an asymptotic ideal at the end of the direction of improvement) of achieving a state like flow in this practice, so you no longer struggle to maintain your attention on nothing. Apparently extremely serene and calm and peaceful. Sounds wonderful.
Flow is different from meditation, to paraphrase what ramblerman said in another comment: meditation is an exercise of directing attention. Being good at that can help you attain "flow" more easily in other activities.
I know I've found meditation to seem to be good practice for when I want to focus my attention deeply.