Perhaps we need to know what your definition of a "soft" blanket might mean.
Soft and easy to wrap around a child like a receiving blanket?
Soft as in drapes well?
Soft as in not stiff? lots of flex?
Soft as in a no weight feel to it? light as a feather?
Soft as in poofy and squishy? with lots of loft?
Depending on your answers, that would skewer what might meet your definition.
Not just the batting could affect it being "soft", also the quilting.
Correct me if I am wrong, but I think of a receiving blanket as simply one layer of flannelette.
You have already planned two layers.
Plus the thickness of the appliques, would create three layers in those spots.
What about using flannelette as your batting?
(or even two layers for batting)
One of my favourite cuddly adult quilts is a traditionally pieced cotton top and bottom with flannelette for the batting. It has a nice drape and hand, and year round, I just love the feel of it against me.