The siftei chachamim (b and i) explains why Rashi offers two pshatim. The primary pshat in this verse is the first (as is usually the case). A second pshat had to be offered because had Rachel asked Yaakov the reason why he cried, he could not tell her that it was because she was not to buried next to him. That information would have pained Rachel greatly. Therefore, a second pshat is offered in our verse. The second pshat is not the principal one because it makes little sense that a tzadik the calibre of Yaakov would cry over monetary loss.

The Ben Ish Chai (b), may his merits protect us, offered a novel interpretation of Yaakov's loud wailing. He explained that normally an adult doesn't raise his voice when he cries but instead weeps quietly. Yaakov raised his voice and cried out loud because people were present and witnessed his kiss. After seeing the kiss, they disparaged Yaakov by whispering that even non-Jews in the generation of the flood were warned about and kept ervah prohibitons.

To cast aside the suspicion that his kiss was not immoral, Yaakov cried out loud -- loud enough so his cries would be heard by the crowd assembled to demonstrate that this kiss was not an illicit one. If his kiss was improper, Yaakov would not be possessed of mind to cry, he would have continued on in his manner in a lightheaded manner against his will. Had Yaakov not raised his voice, the people assembled would have wrongly suspected kosher and pious tzadik.