So I am close to leaving nauvis onto the first non-nauvis planet, and quickly noticed that vulcanus went from a very useful and good choice to nearly useless.
Now, I'm not oposed to a Vulcanus nerf, but in this case, they are too impactful and just hit the wrong things about Vulcanus

The foundry went from a big improvement to ore processing in Nauvis/Gleba/Gaia to completely useless. We already have arc furnaces and casters to process ores efficiently and create molten metals, but considering the Foundry big crafting speed reduction, module slot reduction and massive power increase (roughly 23x power draw), there is no reason to ever use foundries outside of Vulcanus, either as arc furnace replacement (that gets productivity techs) or caster replacement

Big mining drills are fine, compared to the drill options its more speed, range, and lower ore drain. A big improvement, but its important to note that most of the ores in Nauvis come from deep drills, also there are excavators for stone and other base products, so overall its not as major of an improvement as it is in normal space age. The recipe change is fine

Turbo belts got a huge recipe change: electrolyte. This not only makes them dependant on an item exclusive from another planet (technicaly 2 planets since Gaia also has scrap, but you don't go to gaia looking for holmium), which whould be an ok change if it was on small amounts (its not, belts are one of the most used items, so making belts by the hundreds is the norm in smaller factories, the holmium drain is noticeable), but holmium ore is the most annoying planet-exclusive item to mass produce as you need to void all the other junk that comes from scrap

Lastly, artilery does benefit from Vulcanus materials, as the only way to get artilery wagons and an alternative to artilery turrets and shells. But those recipes can easily be avoided, and artilery turrets do most things you whould want artilery wagons, so its a nice reward, but not essential.

So, with these changes, why should I bother with Vulcanus? There are no rewards that make it feel like a good choice, possibly belts but those are now a big hassle over a 33% increase compared to express belts. As a sidenote, electromagnetic plant nerf has similar issues to the foundry, albeit to a lesser extent as the productivity bonus applies to more complex items like circuits, electronic parts, modules, etc

Well the tendency for vanilla space age bases to evolve into hyper-optimizing a relative handful of buildings with base +50% productivity is something ESIR strives to move away from—to that end the asymmetry between buildings tends to ensure niches remain carved out throughout the game instead of guaranteeing one particular entity gets used in every possible case of, IE, smelting.

Regarding Turbo belts requiring Electrolytes, relative to vanilla space age's trivial requirements, it is expected that a significantly higher amount of space logistics will be employed.

Determining that mass production of any given item is annoying is more of an admittance of personal character than it is a critique of the game-play loop.

Neo belts also require Turbos, and the 90/s item speed with the Neo loaders dual lane filters and belt stacking wind up being a noteworthy upgrade.

Presumably you have noticed scrap recycling has 24 possible outputs now? The scrap asteroid crushing recipes each reduce this to 21 outputs.. ;)

The project is ongoing and perhaps Vulcanus deserves a novel reward—does anything on the mod portal come to mind?

Its fine to not want foundry in every step of making ingots, or electromagnetic plants in every step of circuits or whatever, but those really good buildings are sort of the core of space age to push players into the other planets. Think of it as a science pack, but with diferent tasks.

There are diferent aproaches in the "mining ore to get ingots" chain, which is good, but the problem is that with its current stats (mediocre crafting speed and enormous power consumption), there is no reason to ever use foundries in any of those steps, even accounting for the productivity, which is bad because its suposed to be a reward from setting a platform from nauvis to vulcanus, making a new base in vulcanus with all the diferent recipes, and sending the foundries back . If you think the +50% productivity is so bad, you can tone it down, but make them worth using over what we had before going into Vulcanus

In hindsight, turbo belts are ok, its still the original 60/s, and holmium being anoying is not just a personal thing, many other players agree, but I digress. Also only neo loaders require turbo belts, neo belts/undergrounds/splitters use express belts, but in any case neo belts are much after first planet travels

Vulcanus, being a planet themed around molten metals and mettalurgy, should offer rewards similar to that. That's what the foundry is suposed to do, a faster, more efficient way of ore processing. Doesn't need to be both faster and more efficient, but currently its neither.
If you do want players to use the new asteroids more, a reprocessing style recipe for them whould be good, currently there is no way of balancing the 6 new asteroid chunks and it whould make platform designs much better by enabling asteroid chunks to better fit each platform's needs

I'd totally be pleased with deleting Foundry and moving lava processing to arc furnace, then I could reskin arc furnace to foundry. Foundry is just too pretty, I like watching the bucket of molten stuff.

I need more molten / liquid pouring machines too, please and thank you