Some player's such as my self have ships and load outs conducive for generally one purpose. I've got two Corvettes for example. One has an Uber (all cabins) load out, one has a Lift (all cargo bins), they have slightly different fsd's. In both cases, I never accept missions that go one or two jumps from where I'm leaving from. Thus I don't need an "A" graded engineered FSD when I can get buy with a "D" graded engineered FSD. In addition to being cheaper, it's lighter and requires slightly less materials when engineering which means slightly less time grinding materials.
On the other hand I've got a Conda which I utilize for long range jumping around the bubble as well as outside the bubble. Though it's engineered to get 66 ly's per jump. Because of my optional's I only get 60. By choosing different optional's such as one would need for only exploring and not gathering mats or joy riding in an srv which I have four of in addition to canyon flying which needs fighter's which I have 6D's; I'd get 66.
It all boils down to what is the purpose of the ship and it's load out. The same issue comes into play when choosing a thrust-er. My corvette lift needs a bigger or better engineered than my corvette uber does. The reason is the weight of a cabin is factored in when installing it, Cargo Bin's weight are not a factor until they are loaded. Thus the thrust-er installed in my uber is far less than the one in my lift. Prior to Horizon when ships were not able to land on planetary docks, it wasn't an issue. Tis possible now to be over loaded and not be able to leave a planet if and when one has too many bins and they are all full to the max.