TL;DR
To maintain the quality debuff scaling, higher quality speed modules should reduce quality further.What?
Currently, legendary speed modules have a lesser relative reduction in quality to their affected buildings than the normal quality ones. Given the already minor reduction in quality speed modules provide, the quality reduction should scale with module quality, even if not directly (although, this is what I propose)
Shown above is an image reflecting the current scaling of quality reduction per increase in speed, based off the quality of modules. This holds true for all tiers -- as the quality of the module increases, the trade-off between speed and quality favors speed further, with maximum quality speed modules becoming 2.5x better at performing this trade-off than normal modules. (A 60% increase in speed results in a 1% reduction in quality)
Specifically, an approximate 50% increase in building speed, enough to offset the speed reduction of 10 quality modules, will reduce the quality by 1% -- which reduces the buff of those maxed out quality modules from 62% to 61% -- a negligible reduction in quality. This is most prevalent in Cryogenic Plants, which have the whopping 8 module slots.
My proposal is that this value remains the same or increases as the quality of the module increases, to keep the current balance regardless of the variation in quality that a module has -- or to have the current quality reduction for normal modules be the same effective reduction as legendary modules.
Shown above is the same graph, but with the approximation of the quality scaling formula applied to the quality reduction of the modules. This cancels out the denominator, resulting in the ratio being the same across all quality levels.
Adding the same basic quality scaling to the reduction in quality would be simple enough, and ensure the trade-off is identical across all module types -- that is, that an extra 20% increase in speed to a machine results in a 1% reduction in quality.
Going back to the previous example, 10 quality modules with a buff of 62% would instead go to 59.5% -- still a negligible reduction in quality, but at least not as minuscule as it is now.
Why?
The whole concept of 'haste makes waste' becomes kinda moot when you get a large speed buff for a negligible reduction in quality. I think the mechanics as they are do too poor a job of making players think about where they place their quality modules, which was the entire point of the quality debuff on speed modules in the first place.The point of this suggestion is to get players to think more carefully about where speed goes around quality builds, while still making it a trade off which might have merit in specific situations.