I suppose that’s right. Instead of saying:
When they questioned my citizenship, I quickly pulled out my passport.
You could say:
*When they questioned my citizenship, I quick pulled out my passport.
Everyone will understand the idea. The problem is that syntax weighs in its ugly head. Syntax prods us to put an adjective before a noun. If this were German, it wouldn’t matter. But syntax itself starts to define what is an adjective vs. an adverb, in many cases:
*The fast car drove away.
The car drove away really fast.*
These two sentences don’t have the same meaning; the adjective and the adverb have the same form, but the syntax is what makes the difference.
Do we really want to give up the adverb?
), and it’s possible for English to do without them if its speakers deem it necessary.