For us, the short answer is, yes. There are very few wines that do not benefit from the action of pouring wine from the bottle into another container and standing for some time before drinking it. How long you let them "breathe" in this new container, with much more of the wine's surface area exposed to the air, is a matter of personal taste in how you enjoy your wine.
There are really two different actions here. Pouring wine from the bottle into a wide based container and letting stand only a few minutes can alter the taste of the wine. This "carafing" of the wine can add a little elegance, soften rougher tannins, and persuade even the most simple of wines to provide more aromatic enjoyment. Try it! Pour half the bottle in a carafe and leave the other in the bottle. Let stand 3o minutes. Try a sip from a glass with the carafe wine and another with wine from the bottle. If you prefer one over the other after trying a few wines, then that's best for you.
Decanting a wine may have an entirely different purpose. Heavily tannic wines, may leave a deposit ("sediment") on the bottom of the bottle. If you have opened and poured an old Vintage Port, you know exactly what we mean. While this sediment will cause you no harm, its consistency (often gritty) does not enhance your experience of the wine. Wines are carefully decanted to ensure that as much of this sediment as possible stays in the bottle.