But there are good reasons why officers need to become more comfortable with writing search warrant applications, and to delay non-emergency searches until warrants can be obtained.
Warrantless Searches Are Presumed Unreasonable
"Searches conducted outside the judicial process, without prior approval of judge or magistrate, are per se unreasonable under the Fourth Amendment." (Katz v. U.S.) This means whenever you rely on an exception instead of getting a warrant, your prosecutor will have the burden of convincing the court not to suppress resulting evidence.
On the other hand, when you search under a warrant, the defense will have the burden of showing some substantial defect in the warrant, or some mistake in your service of it, before the court could suppress the evidence. This is because the courts have expressed a "preference for police action taken under a warrant as against searches and seizures without one," and have said that "a search under a warrant may be sustainable where one without it would fail." (U.S. v. Ventresca)
Also, even when a Fourth Amendment error occurs, the "good faith" doctrine may save evidence collected under a warrant, while an erroneous warrantless search would generally mean suppression of the evidence, notwithstanding the officer's good faith. "A warrant issued by a magistrate normally suffices to establish that a law enforcement officer has acted in good faith in conducting the search. When an officer acting with objective good faith has obtained a search warrant from a judge or magistrate and acted within its scope, there is no police illegality," and the evidence is therefore not subject to the exclusionary rule. (U.S. v. Leon)