To carry the weight of the LINES !
If a plane ' comes in ' on equal panels , they tend to ' roll up the lines ' ,
whereas a longer inner will lift the inner ( upright or inverted ' and tends to fly the lines TIGHT , of its own accord .
Though thats outside the design criteria of ' pro '
F2B / P. A. , where 1/2 assymetry seems to be preferred ,
being theyre Supposed to stay out there full time . Thus they carry more tip weight .