It is intentional to have G, R and S as 3D View shortcuts to avoid to repeat them in keymap configuration, for each mode, where they are useful.
If you disable G and S shortcuts relative to sculpt mode, they will behave for transforms like R.
If you add a texture with a View mapping, R will show Angle Control menu like in paint modes
G and S shortcuts are anterior to presence of transform tools in sculpt mode.
G is used for Grab brush since creation of sculpt mode.
S was used for Smooth brush until Sculpt Vertex Colors painting was added.
In paint modes, S was used to sample color. So, to bring coherence to keymap, Smooth Brush shortcut was revamped Shift S.
It created an issue. Shift S was already used to enable stabilizer.
So to be more similar to paint modes on one point, sculpt mode became less similar to paint modes on another one.
E is not abandoned if it used to change Stroke method.
You may want to occasionally change stroke method of a brush from Space to Line, Curve, Anchored. You may be perfectly fine, with radius, strength, texture, … multiples settings of a brush and don’t want to specifically save a derivative one, just for Stroke Method.
If GRS are kept for transform operations, S can not be used to sample color. So, it has to be changed in other paint modes, too. R for Angle Control, too.
And Grab brush needs a new shortcut.
But is a shortcut for Elastic brush an higher priority ?
Should specials menu be more specific for such new brush with deformation modes ?
There is no shortcut, in sculpt mode, already used that has no pertinent purpose.
Things are always added because they are making sense, at moment of their addition.
Did new additions make ancient shortcuts use cases obsolete ? Answer is no.
It still makes sense to have shortcuts to call brushes, to change basics of a brush, to call menus for brush settings, to control brush texture settings.
Difference is just that we have more brushes, with more settings and new tools to transform, remesh, mask, paint and apply filters.
We don’t have more keys on keyboard to operate 3 times more manipulations.
So, we have to redefine priorities for default keymap.
But it looks like work will be done for new paint mode, first.
Joe has still several features to add to sculpt mode, from sculpt-dev branch.