Temporary, yes, and easily changeable for mow lines. But design seeks the best solution, which at least trends towards permanence, no? So, is the definition of when to engage an architect reduced to "If we can fix a flub cheap, we won't use an architect?"
My mom used to say, "There's a little trick (or science) to everything." Everything is designed. It is either designed well or designed badly. Not much in between. Even "details" like mowing lines. How they flow and fit the landscape can be attractive and strategic, or it can just be wider or narrower.
Would you rather have someone trained in landscape architecture, who has thought about and executed such things for decades looking at this type of design problem, or super who was assigned the task of changing mowing lines by the green chair yesterday at the meeting? I mean, for a measly $2500, wouldn't it pay to get it closer to visually and strategically correct (albeit, both, particularly the latter are subjective to a degree)?
And, for that matter, not every architect is as strong visually and/or strategically as they ideally might be. I suspect many in house efforts came when they tried an architect on a low ball budget, i.e., we just need you to draw up our ideas, or "we only want to spend $1000 and have you make one visit" and didn't get what they wanted. What they probably need is to pay a bit more and have the gca committed to that project to get the best.
Of course, if they lay it out themselves, they may not ever know just how much better it could be, either. Or, have such an ego that whoever laid it out can't conceive of it being better, i.e., pride of authorship. Or, they just haven't realized or don't care about the above - i.e., It is either designed well or designed badly. Not much in between.
Of course part II, as mentioned there are supers who are quite good at it, having studied design a bit, and more so, having studied their own course even more than quite a bit. So, results no matter how its done are both all over the map, and of course, subject to the whims and opinions of every golfer who plays there. Sometimes, little design issues go back and forth many times at nearly every club, and some public courses, too.