The phrase "are not without importance" is correct and usable in written English.
It can be used to indicate that something does have significance or value, even if it may not be immediately obvious.
Example: "The minor details in the report are not without importance, as they can influence the overall outcome of the project."
Alternatives: "are significant" or "do hold value".
Thus it is not without importance to see that pragmatic principles delineating empirical significance (like Mach's or Quine's Peircean insight) are not ruled out from the start either.
Double-blinded, randomized controlled clinical trials to establish efficacy and safety of novel AEDs are of pivotal importance, but are not without limitations due to their often strict dosing and entry requirements, reducing their applicability to the wider population, e.g. geriatric patients or those with multiple co-occurring conditions.
If, clearly, it is the second that has triumphed, with the results to be seen in the disparate, sometimes jealous, highly specialized disciplines seen today, the first was not without great importance and must also be examined.
His poetry proper (Cinq grands odes [1910; Five Great Odes]) is not without its influence, but the real importance of Claudel's poetic gift lies in the lyrical, epic qualities it infuses into his drama, which will be discussed below.
His reign was not without its clashes, but he understood the importance of respecting the cultural sensitivity of the Han majority.
Despite its centrality to evolutionary theory, and its historical importance, population genetics is not without its critics.
The importance of cholesterol oxidation in the lens is not without significance.
The importance of the neutral effect of aspirin on cardiovascular events is that this drug is not without side effects.
Despite its importance to contemporary understandings of Newton's relation to Cartesianism, and much else besides, De Gravitatione is not without its problems.
