Here are some conventional products that used to have trademarked names: videotape, aspirin, dry ice, cellophane, linoleum, thermos, and heroin. Oh, and also escalators, kerosene, and laundromats.
Trademarks are tricky—almost paradoxical—things: The more popular your product gets, the greater the chance you lose control of its identity. Trademark law recognizes a spectrum of "distinctiveness" when it comes to products' names, ranging from "arbitrary or fanciful" (think Starbucks, Polaroid, and Apple-as-applied-to-computers) to "suggestive" (Whirlpool) to "descriptive" (Saltine crackers) to "generic." And once the Patent and Trademark Office determines that the name of your product—no matter how arbitrary /fanciful/suggestive it was at first—has become generic, you lose your trademark. You get, basically, cellophaned.
To counteract that, companies employ a slew of different strategies—some subtle, some very much less so—to associate their products with their brands in the minds of the public. And to prove, should they face a trademark challenge from a competitor, that they are actively protecting those brand identities. (Not to mention their brands themselves: Band-Aid's TV commercials now feature the adorable voices of children singing, "I am stuck on Band-Aid brand ...")