Only if you think the amount of energy released by burning 16 gallons (US) of petroleum spirit is "large". I'm sorry; I don't agree that "c^2" is an important

Only if you think the amount of energy released by burning 16 gallons (US) of petroleum spirit is "large". I'm sorry; I don't agree that "c^2" is an important part of the equation; it's a constant, so if we're setting aside units, then it's meaningless. And it's just one of several constants; focusing on the speed of light as the key constant is misleading, making the constant of proportionality look "big". But it's not big or small; there's nothing to compare it to, so using comparative adjectives isn't reasonable.