what do you think is the functional significance of protoplasmic streaming?

Answer 1

Protoplasmic or cytosolic streaming is a term for sudden local changes in the cytoplasm from a solid gel-like consistency to a more fluid state, resulting in vigorous flowing movements. This helps maintain an even distribution of metabolites and other cytoplasmic components inside the cell.

("Molecular Biology of the Cell", Alberts et al, 3rd edition)

However there are exceptions where protoplasmic streaming is used for excatly the opposite ie for generating asymmetry, like for generating polarity in the one-cell embryo of C.elegans

(http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Search&db=books&doptcmdl=GenBookHL&term=cytoplasmic+streaming+AND+1385%5Buid%5D&rid=ce2.section.448#449)

Answer 2

Transport of certain organelles (e.g. plastids) is one possible use.