The phrase "are not imperative" is correct and usable in written English.
You can use it when discussing statements, commands, or requests that do not express a necessity or obligation.
Example: "The suggestions provided in the report are not imperative, but they could enhance our overall strategy."
Alternatives: "are not mandatory" or "are not required".
"These are expenditures that are not imperative in this time of fiscal uncertainty," he said.
He said that large-scale cuts to the system -- including the possible closings of lower-volume post offices -- are not imperative, and could actually end up hurting the service in the long run.
As long as finished sequences are not imperative, 454 sequencing can provide advantages in cost and time over classical ABI-Sanger sequencing.
The imperativalist acknowledges that ultimate legislative power may be self-limiting, or limited externally by what public opinion will tolerate, and also that legal systems contain provisions that are not imperatives (for example, permissions, definitions, and so on).
They are more expensive, though, and aren't imperative for sheep.
But its obligation is not imperative.
Music is not imperative merely as an expression of our cultural heritage; music is imperative, period.
Willie Randolph said it was not imperative for Hernández to pitch before the regular season ends Sunday.
Even if you are not friends with your roommate, which is not imperative, simply getting along is very important as cooperation on certain matters can be a deal breaker.
Osborne recognises that it will be a significant hit for Clegg (he tells his Tory staff, 'They are mad to let us do this'), and offers to pass on the proposal telling him the change is not imperative.
I guess it's not imperative for biographers to dwell on their subjects' sexual inclinations, though most would agree it's kind of crucial in Hopkins's case, and Mariani is almost coy on that point.
