That is a fairly recent concept and historically not one that the vast majority of game designers have catered to. Most games have given even less information than we have here, and expect you to figure out the relative strength of various equipment on your own, because the formulas are almost never important and sometimes figuring out how much more powerful the Master Sword is is just part of the game.
The system we have here gives the potencies of attack and healing actions, which allows you to compare the actions within a single job's toolkit to eachother to make reasonable judgements about what is an optimal strategy or rotation, and that's basically all you need to know to devise such a rotation. You simply don't need to know how much stats like weapon damage or mainstat contribute to the damage formulas because it's not going to change the actions' potencies relative to each other, and so doesn't matter.
All you need to know here is that it grants a speed multiplier greater than 1.0. Does it having a 1.25 or 1.5 or 3.0 multiplier affect whether or not you will use it? It's a free, oGCD action with no consequences, and it doesn't compete with any alternative actions that force you to choose between a high speed increase or a low speed increase with other benefits tacked on. Just use it.
Actions where the potency or magnitude of an effect matter have those potencies or magnitudes clearly listed in their tooltips, excepting the aforementioned BLM mechanic (yes, UI/AF should be clearer about their effects) and the exact gauge point gains for some jobs' actions (like Improvisation, which, yes, could use a more explicit tooltip, but ultimately still doesn't affect whether or not it should be used).