(I'm a bit uncomfortable with the whole notion, as it kind of smacks of fooling your servants into wanting to be servants, even though that's absolutely not what's happening - it's just my human bias.)
I wouldn't say it's just human bias. The entire concept of social classes and "one's place" is also human bias (along with everything else attribute to Elven behavior), although one that's depicted as perfectly alright in Middle-earth as long as servants are treated with dignity.
I haven't been able to hear the podcasts, so I can only comment on my own opinion and on "Laws and Customs of the Eldar." I imagine Elves do vary their interests somewhat over their lifetimes, though not really out of boredom (except in the case of Noldor?). I also think a lot of them are what we might call polymaths. The guy sweeping floors is probably also a talented interior decorator, singer, calligraphist, arborist, and cobbler, and will manage to do all of that, including sweeping, in an artistic way. (I don't know what artistic floor-sweeping looks like, but an Elf would.
)
I also imagine that, for the especially back-breaking and unpleasant physical labor, Elves aren't likely to relegate specific individuals to being stuck doing just that for millennia, while others live in more luxury. Not just because that doesn't seem right to me and Elves seem more likely to cooperate and share the most difficult labor. But also because I think Elves can do many things more efficiently and effortlessly than Mortals. They're tougher, stronger, more dextrous, need less sleep, and seem to have everyday "magic" for lack of a better word. Consider farming: humans without industrial machinery have to put back-breaking labor into tilling, planting, weeding, irrigating, and harvesting. Elves no doubt figured out how to farm without tillage (which is more sustainable as well) and can probably make their plants grow better and with fewer weeds just by singing to them. Maybe they can sing the fruit down from the trees instead of climbing up to pick it? An Elven farmer may be what you mean by blue-collar, but they don't have to work as hard as pre-industrial human farmers, and their products are better than ours, too.
Where I agree more with amysrevenge is that in a culture where servants are treated with the dignity and love they deserve, they won't be so likely to hanker for a promotion, even after 948 years. If being a waiter or cleaner/interior decorator is
fun.