In my experience (obviously anecdotal, but take from it what you will), it all comes down to whether you're dismissing the struggles of the student (i.e., "why is this not easy for you") vs the complexity of the problem (i.e., "the problem looks intimidating until you realize this key insight that makes it more routine based on what you already know").
For instance, suppose a student is struggling to use the chain rule to compute $\dfrac{\textrm d}{\textrm dx} \left[ \sin (x^2) \right].$ In that case, it would be unhelpful to say "it's just the chain rule" because that's what they're trying to do.
But now imagine that a student has learned the chain rule and is comfortable applying it, and you're teaching them implicit differentiation. To show them how to compute $\dfrac{\textrm d}{\textrm dx} \left[ y^2 \right],$ you might say something like
I know it looks weird because there's no $x$ in that expression being differentiated. However, if you just write $y$ as a function $y(x),$ then it's easier to see that this is ultimately just boils down to a straightforward application of the chain rule:
$$\dfrac{\textrm d}{\textrm dx} \left[ y(x)^2 \right] = 2y(x) \dfrac{\textrm dy(x)}{\textrm dx} = 2y \dfrac{\textrm dy}{\textrm dx}$$
In this case, the point the phrases "if you just," "it's easier to see," and "a straightforward application" is to highlight key insights that can be used to reduce the complexity of the problem. You're trying to convey that a change of perspective can make this problem feel less intimidating and more routine to the student based on what they already know.
That said, it's easy to overestimate the prior knowledge of the student, which can lead an expert to think they're dismissing the complexity of the problem when they're actually dismissing the struggles of the student.
