Why did Rachel and Le'ah say "due to these reasons, we should follow Hashem's command"? And why did Yakov need to give reasons?
Seforno (Pasuk 14,16): They explained that it is not hard for them to leave, and that he should obey Hashem's command and leave immediately, without asking permission from their father.
Lev Eliyahu (Bereishis p.112): One should not think that he must suffer here to serve Hashem, and then the world to come will be nice. Rather, he should see that Avodas Hashem is best for him also in this world!
רש"י: כי כל העשר - כי זה משמש בלשון אלא: מנין לרש"י לפרש כך?