Doing no research at all is obviously foolish. Assuming what your prospects want can be risky, especially if you assume prospects are just like customers. It’s MBWT again.
But even if you’ve done enough research to know prospects desire X rather than Y, things can still go very wrong. Typical X/Y choices might be low-cost vs. high-quality, or innovative-idea vs. choice-that-won’t-get-me-fired, or beer-with-impressive-badge-value vs. beer-with-manly-badge-value.
If X seems clearly preferred, many brands and (sadly) some agencies will simply hammer “we’ve got X” in hopes that the message sent will be absorbed after 7-times frequency. The ideal ad message, by contrast, gets the audience to internalize “why, they must have X,” a feat requiring considerable creative skill … and far fewer repetitions.
If you doubt marketers are that naive, take this challenge: sharpen your #2 pencil, turn on a local radio or TV station, and score the next ten commercials. How many tell you a benefit vs. tell you a story that lets you assign a benefit? One out of ten? National/network spots will score a higher percentage than local, but it sure won’t be 100.