1)
Why does it say "va'Yisbe'u Me'od"?
1.
Radak: They were too satiated - "Ad Asher Yetzei me'Apechem" (Bamidbar 11:20).
2.
Malbim: One who sins due to desire, once his desire is fulfilled, he regrets his sin. Here they did not regret even after satiation - "Ad Chodesh Yamim Ad Asher Yetzei me'Apechem" (Bamidbar 11:20). Their complaint was regret over leaving Egypt and accepting Mitzvos. They were "Bocheh l'Mishpechosav" (ibid., 10) - over Arayos that were forbidden to them (Shabbos 130a).
