Untold billions are pouring into AI development because its a fascinating area but no company has managed to turn it into a commercial product yet. Customers are so used to voice assistants being a feature of their hardware rather than a product by themselves. Viewed as sophisticated software, most consumers don't even want to pay $2 for a videogame for their phone.
I maintain Apple have had the ability to improve Siri for over a decade but chose not to spend the R&D because they know from anonymous user data that people don't use it for much more than setting reminders, timers and playing songs. The general public just isn't interested in AI as a concept and if anything is more than a little fearful of it.
Companies keep putting it in because honestly they don't have much else to go on. Smartphones have plateaued but not everyone is on the same upgrade cycle so they need to keep the annual snowballing going.
