That's a valid point and does shift the balance somewhat, but not fully in favour of nitrogen-based explosives.
From a practical perspective, at least within Earth's atmosphere, that oxygen is "free". There's not need to carry it with you, though some combustion applications may require feeding it at high rates (turbochargers, compressors, gas turbines, and the like). Most automobiles functions strictly under natural aspiration, and even industrial combustion typically utilises relatively low-power bellows or air introduction.
Rockets, of course, carry their own oxidizer, so we can compare energy densities based on net yield.
The Saturn S-IC (first stage of the Saturn V stack) is powered by the combustion of RP-1 (a highly-refined grade of kerosene) and LOX, liquid oxygen.
The tank sizes were 730,000 L fuel, for which I'm assuming an average density of 0.9g/mL (0.81--1.02 given by Wikipedia), and 1,204,000 L oxidizer, at 1.41 g/mL.
That works out to 657 tonnes of RP-1, 1,374 tonnes of LOX, or a total of 1,511 tonnes.
The fuel alone is 43.5% of the total mass, which means total specific energy is reduced to 17.63 MJ/L, which is still about 3.5--4 times greater than TNT or C4, by comparison.
There's one further question as to whether or not the rocket is tuned to run rich, stoichometric (balanced fuel and oxidizer), or lean. Most LOX rockets burn somewhat rich, based on recollection and Wikipedia, so the LOX quantity is slightly short of what might support complete combustion, though not enough to affect the overall outcome here.
<https://en.wikipedia.org/wiki/S-IC>
<https://en.wikipedia.org/wiki/RP-1>
<https://en.wikipedia.org/wiki/Liquid_oxygen>
<https://en.wikipedia.org/wiki/Rocket_propellant#Mixture_rati...>