Humans can experience internal states so unprecedented we don't have even approximate labels for. Pleasures new to the most jaded, horrors addictive in their cruel novelty.
Incredibly monetizable thoughts and feelings, in short. Inevitably the same neuroengineering that made it possible for brains to experience them was used to monitor and enforce new and profitable forms of intellectual property. Disney multiplied by fifty the size of their neuroscience department. Neuromarketing returned a greedy wraith from the ever-unquiet graveyard of fads. Rooting your brainphone became a federal crime.
(A new poetry underground was born, too. One of open source brain models and AI text generators reverse-engineering words to replicate DRM-locked states of mind. Long strange poems no human could have written and impossible to memorize. Mirages of meaning and whispery syntax that people kept in much-folded printed pages to be read alone at night. But you had to be careful of your brainphone's surveillance: it only took a single illegal feeling for the EULA to kick in and leave you waiting for the cops feeling despair, shame, and something else, something wordless and awful and not in the increasingly limited public domain.)