Your vacation haiku point is spot on. Ocean and emotion rhyme constantly in those short poems. Both words have three syllables, so they fit the form perfectly. I saw a bunch in a online poetry thread last year. Almost every beach haiku used that same pair. It's an easy match for the theme but way overdone.
My friend wrote a bunch of haikus after her trip to the coast. She used "ocean" and "emotion" together in every single one, thinking it was deep. Posted them online and got roasted for using the most obvious rhyme ever. She checked the thread and saw like ten other people with the same combo. Totally killed her vibe for a bit, lol. Now she cringes whenever she spots those words in a poem.
Feel the same about those two words together in poems. I caught myself using that rhyme last year and felt pretty basic after seeing it everywhere. Your friend's cringe is totally valid once you start noticing it.