Prabhupada stated never we should worship demigods for His Mission.
He was always assure with Krishna alone we can fulfill His Mission, spreading Vaishnava culture worldwide with the right understanding of Krishna’s identity.
He is the ultimate supplier of everything. Prabhupada actually showed with his example that even without money, only taking shelter to Krishna, we can establish everything, spreading all over the world but have to take this leap of faith as he did.
But nowadays FISKCONs teachers like Indrayumna Swami and others are taking shelter to demigods. Today they have even established demigod worship in the temples like in New Vrindaban and other facilities all over the globe.
Srila Prabhupada actually spoke strongly against demigod worships, here some quotes from him:
„That is another feature of Lord Caitanya. He taught in that instruction that there is no need of worshiping demigods. The incident is that in India the unmarried girls, they are encouraged to worship Lord Śiva especially in the month of Vaiśākha, March-April. And they will go to the Ganges side and prepare Śivaliṅga, and they’ll… That means Śiva will be pleased upon them to offer a husband like Lord Śiva. Śiva is very peaceful and very great devotee and most powerful at the same time. So that is the ideal husband. So they brought worshipable paraphernalia for worshiping Śiva on the bank of the Ganges, and Caitanya Mahāprabhu, as naughty boy, approached them. “Oh, my dear sister, what you are doing? Oh, you have brought so many nice things. Give it to Me, and Lord Śiva will be very much pleased. Oh, you are worshiping Durga? She is My maidservant and Lord Śiva is a great devotee of Me. So you please offer Me all these things; they will be satisfied. You don’t require to offer separately.” By this, He wanted to instruct that worshiping the Supreme Lord is the appeasement of other demigods. You don’t require[…]“
(Lord Caitanya Play Told to Tamāla Kṛṣṇa – August 4, 1969, Los Angeles)
Here Prabhupada clearly states that demigod worship is not necessary at all.
Only we need is take shelter to the Supreme Personality of Godhead, Krsna.
Morning Walk – November 21, 1975, Bombay
“Jayapataka: Why did Kṛṣṇa have all the demigod worship put in the Vedas?
Jayapataka: They put… Vyāsadeva put all the demigod worship in the Vedas.
Prabhupāda: For the karmīs. Kṣipra bhavati… What is that? Kam kanta…
Jayapataka: Karmanaṁ siddhi.
Prabhupāda: Karmānaṁ siddhi yajanti iha devatā. Who is interested to take bhakti immediately? Nobody is interested.
Jayapataka: They can get their material facilities from Kṛṣṇa also.
Prabhupāda: Yes. That is recommended. First of all śāstra recommends that if you want this thing you worship this deity, this deity. In this way, at last it is said that you can get anything if you worship Kṛṣṇa. That is said. Akāmaḥ sarvo kāma v mokṣa kāma udara dhī tivreṇa bhakti-yogena. That is for the purpose that if he wants to take advantage, material benefit from Kṛṣṇa, then Kṛṣṇa bhajana will be there, gradually they will forget this material benefit. They will become pure devotee. Just like Dhruva Mahārāja became. Svamin kṛtārtho ‘smi vara na yace.“
Prabhupada here clearly says that u have everything supplied if u follow the recommended process. That is worshiping him, in his deity form. There is not need to worship demigods for getting material facilities, it’s only meant for karmis.
In the next quote he clearly states that demigod worshipers have lost their intelligence:
“You may know also that Ramakrishna’s worship of Kali makes him a third class man. In the Bhagavad-gita it is stated that one who worships the demigods just like Brahma, Siva, Indra, Candra or demigoddesses like Kali, Durga, Sarasvati, etc., are described as persons who have lost their intelligence.”
(Letter to Satsvarupa — Los Angeles 25 February, 1968)
Unfortunately many temples in America, Europe, India and beyond are worshiping demigods some daily, some on only special occasions, festivities.
To get a good a good idea about it, I recommend to watch this clip:
To conclude it with Prabhupadas words:
“You know that we have refused even the Hindu people to hold demigod worship in our temple […]
As a matter of fact, we should not allow anyone to hold any function in our temple, otherwise than Vaisnava principle” (Letter to Hamsaduta , 10th October 1968)