I do not pretend to know the minds of the ESV revisers. But there is some justification for their rendering of Genesis 2:16, although exploring the (possible) reasoning cannot be done briefly. Here we go...
Genesis 2:16-17
We need the text, and in this case it is imperative to work from the Hebrew, with the immediate context also in view (I'll stick with ESV for the English, for the sake of convenience):
16 וַיְצַו יְהוָה אֱלֹהִים עַל־הָאָדָם לֵאמֹר
And the LORD God commanded the man, saying,
מִכֹּל עֵץ־הַגָּן אָכֹל תֹּאכֵל
mikkōl ʿēṣ-haggān ʾākōl tōʾkēl
“You may surely eat of every tree of the garden,
17 וּמֵעֵץ הַדַּעַת טוֹב וָרָע לֹא תֹאכַל מִמֶּנּוּ
but of the tree of the knowledge of good and evil you shall not eat,
כִּי בְּיוֹם אֲכָלְךָ מִמֶּנּוּ מוֹת תָּמוּת
kî bĕyôm ʾăkolĕkā mimmennû môt tāmût
for in the day that you eat of it you shall surely die.”
The words in bold in v. 16 are the point of the question. It is a distinctive construction in Hebrew, combining the "infinitive absolute" form of the verb (ʾākōl, "eat") with a "finite" form (tōʾkēl, Qal imperfect, 2nd person masculine singular, "you shall eat").
This same construction (Inf. abs. + finite form) occurs also in the next verse, and is also in bold: "you shall surely die" = inf. abs. (môt, "die") and finite form (tāmût, "you shall die").
So, to reflect this in an entirely un-idiomatic rendering of the sort you might get in an interlinear gloss, the verses could be "translated" this way:
And the LORD God commanded the man, saying
“From every tree of the garden eat you shall eat
but from the tree of the knowledge of good and evil you shall not eat,
because in the day of your eating from it die you shall die.”
And what does that mean?!
Classical Hebrew's "Infinitive Absolute"
Hebrew has two "infinitives", the "infinitive construct" which is closer to what English speakers would think of as an infinitive -- the "unmarked base form of the verb", often used with "to", but not necessarily -- and the "infinitive absolute" a "verbal noun of action or state",1 or, in more of a thumbnail definition, a form giving the bare verbal idea.
A distinctive feature of classical Hebrew is the use of the infinitive absolute (I'll abbreviate as inf.abs. in what follows) with a finite form of the verb, that is, a form that is inflected for person, gender, number, etc. Genesis 2:16-17 gives us two examples of this construction, as we noted above.
One explanation
How is this distinctive construction to be understood? Older grammars, and many teaching grammars, explained it as an "emphatic" construction: the inf.abs. emphasizing the verbal notion in context. Some go further, claiming that the order of the components (i.e., "1inf.abs. + 2finite" contrasts with "1finite + 2inf.abs.") brings a different nuance: emphatic when the inf.abs. precedes the finite form but durative when the inf.abs. follows.
I don't believe this latter claim is widely followed now. But the notion that the inf.abs. somehow reinforces the verbal idea remains widespread, and so it is explained by Gesenius-Kautzsch-Cowley.2
This accounts for the majority of English translations of Genesis 2:16 - how do you "reinforce" or emphasize the verbal idea of "eating"? By bountiful, plentiful, free eating, is one way, and thus it was taken as far back as the KJV.
Another explanation
However, more recent explanations of the inf.abs. find a different nuance to this construction (or perhaps, a more full explanation), arguing that the inf.abs. does not (only? always?) emphasize the "verbal idea" ("eating", in the case of Gen 2:16):
It is only from the context that the nuance added by the infinitive can be deduced in each case. Usually the emphasis does not bear on the verbal action itself, but on a modality, which is thus strengthened.3
The difference taking on board this notion makes can be clearly seen in this comparison by Scott Callaham:4

If, as Joüon & Muraoka and Callaham claim, the emphasis brought in this case falls on the modality in context (here, permission) rather than the verbal idea (here, "eating"), then a translation much like the ESV's can capture it:
You shall surely [I'm permitting/commanding you to] eat from every tree, EXCEPT...
Conclusion
I don't think -- although I don't know -- that the ESV's rendering owes much to Calvin.5 It seems more likely to me that either the ESV revisers were "balancing" the two inf.abs. constructions in vv. 16 and 17, or that they had in mind the "modality" emphasis of the inf.abs., prefering that nuance here (as does Callaham, see note 4) over the notion of gluttony.
Notes
- So Joüon-Muraoka, A Grammar of Biblical Hebrew, §123.
- See GKC, §113.
- Joüon-Muraoka, §123d, bold added. See also Muraoka's earlier treatment in his Emphatic Words and Structures in Biblical Hebrew (Brill, 1985), pp. 83-92.
- S. Callaham, Modality and the Biblical Hebrew Infinitive Absolute (Otto Harrassowitz Verlag, 2010), pp. 14-16 and 123-123.
- Calvin stresses the liberality of the divine command, but doesn't comment on this Hebrew construction directly.