1. The cost is very high. There is tons and tons of pointless dialogue you’d need to slog through to get to any good bits.
2. The UI is slow and requires tapping a after ~2 lines of text, so an entire conversation ends up being 10+ button presses.
3. All of the text is provided in generic chat bubbles with no interesting/unique/personal touches. The only personal touches are pokemon’s made up noises which should be sounds.
Compare this to a game like Skyrim, where you find handwritten letters, old books, etc
Edit - I feel the need to communicate that the game is incredibly fun and definitely worth playing! The annoying dialogue is hugely outweighed by the great gameplay mechanics.