Usability test results revealed that our "clean" user interface was indeed the confusing one

It took an entire sprint to strip the labels from our dashboard, as the designer was convinced that text made it feel cluttered. Just icons, very little chrome, the kind of UI that makes great shots in the portfolio.

Then we conducted five user testing sessions, and four out of five participants stopped at the same icon for more than ten seconds before pressing it, and two pressed a wrong button altogether and then corrected themselves.

We added two words under each icon, retested, and everyone performed perfectly after that.

It made me wonder about how much of what we consider "clean design" is really designed for its user versus for its creator who will present it later. Has anything similar happened to anyone?