Want To Be Elevated

Why did Klal Yisroel complain about the issur arayot only after the man fell? 

Moshe Rabbenu says מאין לי בשר לתת לכל העם הזה כי יבכו עלי לאמר תנה לנו בשר ונאכלה.  What was he questioning, he knew Hashem could give them meat?  The Imrei Chayim explains that the tzaddik can only ask for the nation if he feels on some level some of the same need.  Moshe Rabbenu was so pure he did not find any iota of desire in him to ask this request from Hashem.  

The Malbim says here that the man was a spiritual food that only came down in a gashmi form because it is placed in this world.  However, one that wanted a gashmi pleasure would not be satiated by man.  That is why the people cried out for meat, they were missing the gashmi connection.  At this point when they realized that there were expected to grow into a role of total ruchniut they cried about the ariyot as well.  They wanted no part of such a life style.  Once there desires for gashmiut were opened, the floodgates opened.  Moshe Rabbenu could not connect to them on this level for he has far surpassed this not even eating on his journey to Sinai and separating from his wife. (See Mayan Beis Hashoavah.)  When a person strives toward ruchiut then then they can have a connection to Moshe and can be elevated slowly and surely but when one refuses and is afraid to be elevated, there is no hope.