This already kind of exists if the parameter supports a curve.
Size and position parameters as you show in your screenshot do not support a curve because it is a combination of 4 parameters (X, Y, Width, Height).
Further to your request on the curve parameters, I doubt we will ever add that as it creates too much visual clutter to discern the current value line from the mid-levels. Visualize my screenshot above with additional lines at -0.5, 1.0, and 0.5. Next visualize that with multiple parameters and you will have way too many lines to look at
And that is before reducing the track height from the default, which is common.