Why is anger better than laughter?
Rav Sadya Gaon: Seriousness in life of this world is better than laughter.
Rashi (citing Koheles Rabah): If Midas ha'Din pursues someone, he should not be pained. It would have been better for Dor ha'Mabul had Hashem showed to them a face angry due to their Aveiros, rather than jesting with them. Had He shown anger, they would have repented. It would have been better for Adoniyahu had David grieved him over every Yeserah (misdeed), than the laughter that he showed to him; in the end, he was killed.
Rashbam: If one thinks about the day of death, "Sof Kol ha'Adam" (2), he is not happy. This is better than laughter in Beis ha'Mishteh; refer to 7:3:3:3.
Ri Kara #1: This explains why going to Beis ha'Evel is better than going to Beis ha'Mishteh. The former brings pain and a sad face - in the end he improves his heart. He puts to his heart that this is the end of man, and decides to fix his ways and deeds; in the end, he improves his heart and repents from his evil way. Laughter nullifies fear [of Hashem], "v'Acharisah Simchah Sugah" (Mishlei 14:13).
Ri Kara #2: Refer to 7:3:3:4.
Rid citing Koheles Rabah: The anger that one shows to his children is better than smiling at them.
Seforno: One can acquire a good name only through anger at the Nefesh that desires, and rebuking it. That anger is better than laughter and enjoyment of its deeds.
Metzudas David: If one sinned against his colleague and [the latter] shows anger to him, this is better than a happy face. Nature is, via showing any angry face, his anger is assuaged and he will not take vengeance. If he shows a happy face, the hatred is hidden in his heart, and he will not have mercy when he finds the right time to take vengeance.
The Gemara (Shabbos 30b) explains "li'Schok Amarti Mehulal" (2:2), i.e. it is praiseworthy. Here it says that "Tov Ka'as mi'Sechok" (even anger is better than laughter)! .
Refer to 2:2:3:1 and the note there.
Ibn Ezra #1: Shabbos 30b brings several contradictions between verses of Koheles. Refer to 12:9:1:5 and the note there.
Ibn Ezra #2: Since a verse testified that there will not be anyone as wise as Shlomo (Melachim I, 3:12), we know that there is no contradiction in his words; "Kulam Nechochim l'Mevin vi'Ysharim mi'Motze'ei Da'as" (Mishlei 8:9). Here, Ka'as refers to the Ru'ach; refer to 7:3:3:2*.
Erech Apayim 2:1: Sometimes, for a Mitzvah, anger is good - only with a show of anger on his face, but there is no adamancy in his heart.
What is the meaning of "Ki v'Ro'a Panim Yitav Lev"?
Rav Sadya Gaon: Via facial anger, the heart is improved (Rashi - he improves his ways).
Ibn Ezra: There are three Nefashos in man. (a) Nefesh ha'Tzomachas is found even in vegetation. It overpowers for a certain time, and causes growth. It desires and needs to eat; in man, it also wants to rejoice and have Bi'ah; we call this Stam 'Nefesh'. (b) Nefesh Behemis (Ru'ach), found in living beings; it has the five senses, and moves. (c) The Neshamah speaks, has Chachmah, and distinguishes Emes from Sheker. "Lev" is intellect to fulfill the desires of each Nefesh in its time. It helps him with Mitzvos, and puts every matter in its measure. Ro'a Panim is worry - "Madu'a Peneichem Ra'im" (Bereishis 40:7). 1
Rashbam: Sadness due to thinking about the day of death, it improves his heart, so he will not sin.
Ri Kara: Anyone who worries has Ro'a Panim. Worry in the heart causes him to fix the matter that he worries about; he improves his heart.
Rid: A cross face causes his children to straighten their ways, and improve his 2 heart.
Seforno: A cross face towards the Nefesh that desires, it improves the power of intellect in investigation and deed.
Ibn Ezra: When the Nefesh gets stronger, the Neshamah weakens, and it cannot stand against it, for the body and all its Yetzarim help the Nefesh. Therefore, one who engages in eating and drinking will never get wise. When the Neshamah joins with Ru'ach, it overpowers the Nefesh, and its eyes open to understand Chachmos ha'Geviyos (of the land and sky). It cannot understand higher Chachmos (of the non-physical) due to the Ru'ach, which seeks authority, and breeds anger - "Al Tevahel b'Ruchacha Lich'os" (9; refer to 11:10:1:4). The Neshamah must overpower the Ru'ach. "Ki Cha'as b'Cheik Kesilim Yanu'ach" (ibid.) - it never leaves a Kesil. It is found in a Chacham only when needed (refer to 1:18:1:5).
His heart implies the father's. I.e. he is happy when his children fix their ways. (PF)