Interesting comment that positions Rama as a conservative of the old order, while KrSNa-avataram marked the dawn of a new era, with new rules. A radical figure

Even Al-Biruni goes to great lengths to describe vAsudeva as a v radical figure who changed many things in Indian life https://twitter.com/_Satchitananda/status/1250755281648267266

It's fair to view the legend of krSNa-devakIputra as being central to the rise of new religious ideas in the course of 1st millennium BCE

Rise of bhAgavata religion, pAncharAtra, devotional theism

I guess these were radical shifts. The religion of vAsudEva was central to this

This likely meant a shift in emphasis from the old vaIdIka rituals to agamic puja rituals

A shift towards "vegetarian offerings" - growth of vegetarianism

Greater egalitarianism in religion

And rise of sectarian religion

A couple of verses from the Bhagavad Gita itself - that early text in the bhAgavata tradition, which underline the radicalism of the movement

पत्रं पुष्पं फलं तोयं यो मे भक्त्या प्रयच्छति |
तदहं भक्त्युपहृतमश्नामि प्रयतात्मन: || 26||

Translation -

""If one offers to Me with devotion a leaf, a flower, a fruit, or even water, I delightfully partake of that article offered with love by My devotee in pure consciousness:"

Notice the push for simplification, the drive towards Bhakti.

Another verse emphasizing the growth of sectarianism

"येऽप्यन्यदेवता भक्ता यजन्ते श्रद्धयान्विता: |
तेऽपि मामेव कौन्तेय यजन्त्यविधिपूर्वकम् || 23||

"O son of Kunti, even those devotees who faithfully worship other gods also worship Me. But they do so by the wrong method"

The radicalism is unmistakable...

This had a telling effect on Indian religion and Indian life, without necessarily causing a rupture or total discontinuity with the old religion

I guess this is one reason why the modern Hindu-Right with its emphasis on harking back to "Vedic times" and "Vedic religion" and its very strong aversion to monotheism, likely relates to Rama better than KrSNa.

Because Rama strikes you as a conservative hero. KrSNa a radical

krSNa devakIputra's radicalism is nowhere more evident than in the fascinating account of his little tussle with Indra in the Harivamsa - an appendix to the Mahabharata that describes his early life

I am referring to his suspension of the Indra-Yajna and the retaliation of Indra

While staying in Gokula / Vrindavan, krSNa one day asks his fellow countrymen -

"What is that sacrifice for which you are all filled with delight"?

One of the milkmen responds -

"O Subduer of the enemies. Indra, the king of the celestials is the master of the clouds....Commanded by him and embellished by his bow, the clouds produce corns with new showers of rain...."

"For this reason, from time immemorial, and coming down from one family to another, this festival is being celebrated"

krSNa protests against the Indra Yajna.

Addressing the milkmen, he says -

"We are all milkmen who range the forest. The precious cows constitute our subsistence. Cultivation is the means of subsistence to the cultivators, merchandise to the merchants, and the cows to us"

"The respective profession of each caste is their great God, and is worship-worthy"

This is followed by a Yajna in honor of the mountains and the kine. Instead of Indra.

The source of livelihood is elevated to a status worthy of Yajna. Indra Yajna is discontinued

You could argue that krSNa here is laying the foundation of his later doctrine of Karma in the Gita - where duty is glorified. Where performance of duty itself assumes a sacred quality. Equivalent to worship

Indra is enraged by the action of the Gokul-vAsis who have "disrespected" him by following the instructions of vasudeva's son.

"All these inhabitants of Vrindavana are now attached to Damodara. Nanda and other Gopas have grown inimical to my festival"

"Stationed on my elephant Airavata, I shall discharge dreadful rain, winds and showers. With these dreadful showers, we will kill all the inhabitants and cows of Vraja"

As the rain pours down, krSNa comes to the rescue.

"I knew before that this will come to pass. ...I will uproot this best of mountains Govardhana containing forests and woods, and convert it into an asylum for the cows"

The great Indra comes down to the earth to witness this spectacle -

Again from Harivamsa -

"He saw there the immortal Vishnu assuming the guise of a milkman.....KrsNa bearing the mystic mark of Srivatsa and resembling a dark blue lotus"

He acknowledges his anger, and KrSNa's feat in countering him successfully

"O KrsNa. I was enraged on account of the suspension of my sacrifice. And therefore I sent down this excessive rain over seven nights,.... But you have put down this terrible shower in my very presence"

To my mind this entire episode underscores KrsNa's radicalism

A pivotal shift in Indian religion during the Axial age

The shift in emphasis from the old sacrificial practices to a new normal based on devotion and worship of livelihood ( later formalized as Bhakti & Karma yoga)

It also marks that rare occasion in Epic literature where Indra clearly is foiled by krSNa

Indra as we are all aware is the most frequently mentioned deity in Ramayana. Clearly the most pre-eminent of Vedic gods for much of the early Iron Age

We now see a Vishnu-centric theology emerging. Where an incarnation of Vishnu is quite literally the "protector" and "nourisher" of the laity.

Nowhere is the radicalism of KrSNa and early Vaishnavism more evident than in the Govardhana episode

Post-script : The translations are paraphrased from Manmata Nath Dutta's translation of Harivamsa in the 1890s.

Also thanks to @SoliloqVish for reminding me of this episode (which I was aware of, but had not linked it in the context of krSNa's radicalism)

Post-script 2 : krSNa's explicit defense of worshipping one's means of livelihood and the kine / cows ties up pretty well with what Al Biruni heard from brahmins around him in 11th cen

"Before the age of Bharata war (i.e age of vAsudeva), we used to eat cow meat. But not since"