Frame interpolation is a thing? There's ridiculously good interpolation techniques that sacrifice almost 0 quality.
These only work well with certain types of art. Pixel art usually looks pretty awful with them; we've tried, with lots of different programs and websites. Cleaning up the sprite while keeping the "interpolated frames aesthetic" consistent would take about as long for our artist as just doing the extra frames themselves in their own style.
It especially looks bad when you have characters with our cartoony-ish proportions, and even worse when it comes to different positions where body parts are hidden and the program can't figure it out.
And, even if it did work perfectly, interpolation just looks sloppy, to be honest. It gives off a "Johnny Test Flash Animation" vibe and ruins the general feel of the aesthetic we're going for.
If there were a way to make it genuinely hand-draw pixel art animation frame by frame with the interpolation like what our artist is doing now, then we'd be for it, but as it is, the technology still has a way to go.
Here's a few examples (and these are some of the best ones we could get);
The original, above; it has weight to it, impact, the thrusts have solid "oomph" to them.
A 40 FPS version (as the original is 10 FPS, so this is 4x) with DAIN; the wings and the tail look janky, to say the least, not something that looks good at all. The animation also feels very "soft"; it looks more like he's just sort of lightly gliding his pelvis back and forth, not having rough sex.
A 40 FPS version with RIFE: the wings look a little bit better, as does the tail, but they still both look janky. The thrusts still appear soft, too.
And here's a 20 FPS version, just to compare, again with RIFE;
The wings don't have as much of an issue, but the tail is still distorted.
The thrusts don't look
as soft, but they still feel somewhat softer than the original... which means even with this, we'd be sacrificing quality, as in, the original intent of the feel of the animation.
This is again, one of the best examples of it; most of the other animations end up horribly bugged.
Besides, having slow moving sprites in a 60 fps engine isn't a bad thing. People want 60 frames simply because movement in platformers (or any other game for this matter) is much better at 60 frames. Your programmer should probably know that.
More frames does result in better control, this is true, but just to be clear, the
game's visuals are locked at 30 FPS.
The game itself is running, on most computers, upwards of 500+ FPS. Meaning, it's registering your input much, much more often than just 30 FPS.
Finally, honestly, it just looks weird to see sprites animating at 30 FPS, while projectiles are moving at 60 FPS. We've tried it in-engine by unlocking it, and it just feels and plays "off"; the protagonist looks like they're gliding along even if we speed or slow their animations up, instead of walking, movement doesn't feel "weighty" anymore, it gives almost a Roger Rabbit feel like we grabbed people from the "30 FPS world" and stuck them in the "60 FPS world".
Here's a video about it;