Ah, but are the people enjoying ikra in real life with the condiments eating the top class finest ikra that there is to offer? Like, to be fair to Mariko there, she actually said that using the eggs and stuff is acceptable, but only if you're eating the cheap caviar. Top class caviar don't need them.
Yamaoka himself in that one chapter with the gold spoons also used only pure caviar on rye bread, so it indicates that the author does think that top notch caviar ought to be eaten plain or with just the bread.