u/xvector did a good job explaining why this dynamic exists
That aside, what exactly is suspect about finding meaning or joy in work? Is the quintessential experience meant to be soulless and grating?
Of course not. Few things in life are more fulfilling than a job you absolutely love and are excited to whack at every single day.
But your question raises another one of equal stature: Is the quintessential experience meant to be a job? If we are creative enough to make rocks that can learn to do our jobs for us, surely we are creative enough to craft an economic model which allows us who no longer need to work to paint or write poetry or rebuild antique engines without needing to starve?
As far as crafting a post-scarcity economic model goes, it's not the problem of dreaming one up, it's the pervasiveness of scarcity. Even if all of humanity's basic necessities are one day a given, scarcity won't disappear, just shift around (maybe as transportation for the otherwise-infinite supply of consumer goods? Or living space away from dense urban centers? Maybe even the kind of heuristic analysis abilities humans are unmatched in to keep the matter replicators functioning?)
More to the point, saying that this kind of luxury will exist in a thousand years doesn't nullify the concerns of the present, and probably wouldn't convince most people to forfeit their employment to machines likely owned by the uppermost classes.
I think there's a distinction in that I was referring to "knowledge work" which isn't explicitly creative/expressive/stimulating. Many would classify much of research or law as "boring" even though they are knowledge work.
>what exactly is suspect about finding meaning or joy in work?
I did not mean it as wrong to find joy in your work. On the contrary, I think that's a worthwhile goal. But the distinction I make is that any work can be found to be fulfilling. It's the distinction between "finding your passion" and "cultivating your passion." I've worked with people who found meaning in their job cleaning offices and others who treated the design of rockets as soul-crushing. I think it has more to do with the person than the job. So I push back a bit on the false dichotomy created by classifying "knowledge" jobs as inherently worth saving from automation while manual work should be fodder for it. I also think the focus on a job for fulfillment is a bit of a red-herring. I think what people really need are to be valued members of society and, for many, a job is a means to that end (and maybe not even a good one).