Note 1: Corrected to account for more typical anime framerates (8-12 fps), rather than 24 fps.
If you’re going to be making a piece of animation, you’re obviously going to need some animators to draw some things. But anime budgets are tight, and the production costs in the industry are such that animation might not always be the best way for directors to maximize the bang they get for their buck. Anime salary data is pretty sparse, but I found enough information on certain costs to do a quick, naive calculation comparing the relative worth of in-between animation and voice acting.
For starters, let’s take the cost of in-betweening a scene with lots of motion; in-between work is estimated to earn roughly 220 yen per frame in pay for the people who draw them (a payout rate which notably hasn’t really kept up with inflation). If you want motion in a scene to look smooth, you’re probably going to have to animate it at 24 frames per second. 24 fps produces an in-between cost of 220*24=5280 yen/second for a nicely-animated scene.* This is not the actual rate for most anime, though, the majority are drawn at 8 or 12 fps, then duplicated up to 24 fps. At a 12 fps rate, it only costs 2640 yen/second.
Next, according to this myanimelist news bit, seiyuu pay grades can range from 15,000 yen (for grass-green rookies) to 58,000 yen (for huge names) per episode. So, assuming there’s always a large amount of rookie seiyuu talent, the estimated industry value above replacement level for a top-flight voice actor or actress is about 43,000 yen.
Combining those two figures, that means that the best anime voice acting performance money can buy has equivalent value on the production side to that of a really smoothly-animated 8 second scene (43,000/5280=8.14 seconds), or 16 seconds of a more typical anime-motion scene, every episode. This partially answers the question of how voice actors are valued by producers relative to other contributors in anime. That’s likely going to strike most people as too high or too low a value, but that’s kind of why that is where it is.** People have a million different opinions on what makes anime as a whole good and all of those are valid (in a producer’s view) so long as they represent potential customers.***
A more complicated question, one I’ve struggled to even begin addressing, is how to somehow quantify the value of a voice actor in terms of ability to draw in sales. Entertainment sales are a chaotic system where small decisions have big consequences and the whole is rarely simply the sum of its parts. It would be really interesting to take that value and then see how each of those two production choices benefited a show’s ultimate reception, but there are so many other variables that go into a completed anime episode that such a comparison is functionally very close to impossible.
*That animators are horrifically underpaid is pretty well documented, which makes me feel bad to write this in static terms rather than as a “triple all animator salaries” editorial. As the mal source for salaries notes, it’s not like most seiyuu have it easy either.
**Also really opens the door for arguments about how Gaworare could or couldn’t justify shoddy animation when it had an all-fame cast. If you, y’know, find that sort of thing fun. On one hand, the source (a sub-10k light novel) might not have been worth it to begin with, and people might only have tuned in for the voice actors. On the other hand, scrapping 10 people worth of recognizable-voice cast members for greenhorns could have given the staff freedom to take the series in an interesting aesthetic direction (which may have ultimately fell flat anyway). It’s a counterfactual with no definite answer, but I bring it up because you could plug about 20 other shows into that name slot and have effectively the same discussion. Still one with no definite answer because, again, complex systems.
***This is why Kishi Seiji, road warrior keeps getting jobs even though “everything” he does is “at best subpar”; a solid fraction of paying customers saw his stuff and judged it differently than the those who use capslock to angrily complain about him being employed. It’s that simple. My stance will be the same until I stop enjoying his shows (unlikely, as triple-Yu was a thing of pure beauty though 2) – he’s been bearing a load both herculean and qualitatively different from what other notable directors handle, and the peaks of his past decade represent his abilities better than the valleys do.