BG Chap 10 - Reasons why Arjuna ask Kṛṣṇa to reveal His opulences
(a) To keep thinking of Kṛṣṇa to gain unflinching bhakti.
Although Kṛṣṇa had explained that He is everything (ahaṁ sarvasya prabhavaḥ), Arjuna requests Kṛṣṇa to speak about His divine opulences (vibhūtis) by which He pervades this universe, so that Arjuna could keep thinking of Kṛṣṇa. At the end of chapter six, Kṛṣṇa had asked Arjuna to always abide in Him (mad-gatenāntar-ātmanā), and at the end of chapter nine, He had asked Arjuna to always think of Him (man-manā). And earlier in this chapter Kṛṣṇa said that by knowing His vibhūtis, one can become fixed in unflinching bhakti. Arjuna asks Kṛṣṇa by what method he could know the Lord constantly, and in which objects should he think of the Lord while meditating.
(b) To benefit the common man.
Arjuna is asking these so that the common man can understand the all-pervading nature of the Lord, and also because the common man finds it easier to concentrate the mind on physical representations. He addresses Kṛṣṇa specifically as yogin because Śrī Kṛṣṇa is the master of the yoga-māyā energy, by which He is covered and uncovered to the common man. The common man who has no love for Kṛṣṇa cannot always think of Kṛṣṇa; therefore he has to think materially.
(c) No satiation hearing Kṛṣṇa’s glories.
Kṛṣṇa had already stated that He is the source of everything and that everything that exists is His vibhūti, and knowing this one worships Him in bhakti yoga. But Arjuna says that Janārdana, by the sweetness of His instructions, creates longing in people like him (jana) and agitates (ardana) them. Arjuna’s ears are acquiring the ability to taste, as if they were tongues, and makes him beg for more as he finds no satiation. One can never be satiated even though one continuously hears the transcendental pastimes of Kṛṣṇa, who is glorified by excellent prayers. Those who have entered into a transcendental relationship with Kṛṣṇa relish at every step the descriptions of the pastimes of the Lord. (Śrīmad-Bhāgavatam 1.1.19)