Most grammarians offer no explanation for this. What may be said by way of explanation—and Allah knows best—is that lām relates to the subject in meaning. For example, you ask, li-man hādhā (“Whose is this?”), and the reply is li-Zayd (“Zayd’s”), thus using (1) lām. By contrast, ilā relates to the object in meaning: you ask, ilā man yasilu hādhā al-kitāb (“To whom does this letter go?”), and the reply is ilā ‘Abd Allāh (“To ‘Abd Allāh”). The underlying reason is that lām primarily denotes ownership, particular association, or entitlement. Ownership and entitlement (2) belong only to the subject who owns and is entitled; ilā, meanwhile, denotes the endpoint. That endpoint is the ultimate limit of what the action entails, so it (3) is more appropriately associated with the object, since it completes what the action entails.
An example of an exclamation concerning an action undergone by the object is what Ka‘b ibn Zuhayr said about the Prophet, may Allah bless him and grant him peace:
“Indeed, when I speak to him, he is more fearsome to me—
Having been told, ‘You will be imprisoned and slain’—
Than a lion whose lair lies on the moist earth,
In the valley of ‘Aththar, thicket behind thicket.” (4)
(1) n: “fa-ta’tī” (“so it comes,” with a feminine verb). The imperfect-tense prefix is undotted in k and ‘, both here and in “fa-yaqūlu” (“so he says”) below.
(2) “And ownership and entitlement” is omitted from all editions of the book except the Indian edition.
(3) mb: “fa-huwa” (“so it is,” with a masculine pronoun). j reads “bi-l-fi‘l fa-huwa” (“with the action, so it is”), which may be an error.
(4) The two verses appear with this wording in the source manuscripts. Ibn ‘Asfūr also quotes them thus in al-Muqarrab (1:71–72) and his commentary on Jumal al-Zajjājī (1:577). I have not found the reading “bi-tharā’ al-ard” (“on the moist earth”) elsewhere. The closest reading is “bi-darā’ al-ard” (“amid the earth’s thickets”), as in Sīrat Ibn Hishām (2:511–512). Darā’ means densely intertwined trees in a valley. As for “tharā’ al-ard” here, it may be an instance of madd al-maqsūr (changing a word’s final -ā to -ā’), which the Kufan grammarians and some Basran grammarians permitted. See Ibn ‘Asfūr, Darā’ir al-Shi‘r, p. 38. In the printed editions other than the Indian edition, the first hemistich of the second verse reads:
“Than a lion abiding in its lair, one of the lions, whose dwelling…”
This is an alteration introduced by some publishers. This reading appears in Ibn Hishām’s Sharh Qasīdat Ka‘b (p. 76, al-Maymaniyya edition), Lisān al-‘Arab (entry kh-d-r), and elsewhere. See also the two verses with another reading in his Dīwān with al-Sukkarī’s commentary, p. 21.