My pain points are largely in creating/editing articles. I use Pages largely as a news and reviews page and the forums piggyback off of that. I have no trouble finding content to create, for my niche it is a veritable firehose to stand in front of, but getting it created in Pages with the right format is tedious.
I'd love:
a better method for placing pictures, setting alt text, setting captions.
More options for what a gallery looks like when I place a link to one. See @opentype's SuperReviews as one example of what I'd like to do, but with the Gallery system.
Multi-column formatting
Some sort of widget or block system where I can place an Ad widget inline with the text.
Compatibility with Grammerly - Seriously, it's a pain to write it in Word so the article gets checked with Grammerly and then cut-paste-format into Pages.
A lot of my slow-down with generating content. There is so much of it everyday that I have to pick and choose, but getting it posted is painful.
I'd argue that the forum in IPS software is largely feature complete and any improvements would be just slightly incremental. Pages, Gallery, Clubs, is where attention is sorely needed.
I said here many years ago that IPS has the potential to be the paid Wordpress beater if Pages was improved. I still see that potential.