There is no "one size fits all" when it comes to tokenmetrics. The tokenmetrics of existing altcoin projects are largely experiment and inflationary token supply has become a new shift in how token supply are structured. Instead of having all the supply available at launch (and unlocked) which could impact the price, most teams just lock some of the token supply and unlock it linearly. It's not the best approach and it has its downside but it's the best for now except someone comes up with a much better way to structure token metrics in the future.