I believe Vulcan's were natural telepaths, but had no real range; most of them were touch-telepaths. You may notice that every time you see Spock, Sarek, etc., use the 'Mind-Meld', they first touch the target in certain ways. (A few notable exceptions, like Spock influencing someone through a wall, required intense effort and concentration.)
An exception, of course, was Spock's brother from 'The Final Frontier', but he was just that; an exception. There were other exceptions, but it wasn't the norm, so it wasn't a common communication method.
From Memory Alpha,
The most famous aspect of the Vulcan brain was the inherent telepathic abilities, such as the Vulcan mind meld. Vulcans were natural touch-telepaths. Though considerable training was required to utilize this ability to the fullest (this would be performing the fal-tor-pan), simpler contacts did not require any concentration, training or even conscious knowledge of the act. (VOY: "Blood Fever")
Stronger minds were capable of non-contact telepathic projection and scanning, usually over short distances, (TOS: "The Devil in the Dark", "The Omega Glory"; VOY: "Random Thoughts", "Prey") but sometimes even over interstellar distances. (TOS: "The Immunity Syndrome"; Star Trek: The Motion Picture)
In general, though, touch-telepathy wouldn't be a very safe thing to use on an unknown being, and the touch aspect of it makes it impractical for general communication.