I like the term App Coin. Alt coin is definitely an outdated term. One of the most revolutionary features of crypto (and i feel rarely talked about as such) is that it encourages and incentivizes a creative feedback loop on the system to help it grow. This is obvious in steem on the surface with posts acting as crowdfunding of advertisements and feedback on features, etc. It was true long before with bitcoin, the whole community was involved in extending bitcoin into the physical, finding merchants to accept it as payment, creating easier and safer ways to send and receive bitcoin, creating infographics and videos to help people understand it. There is built in reward to help it grow, add flexibility to features, strengthen it and then create services that integrate the coin to extend its use further.
its a new social/economic entity type entirely. This is key to the innovation behind crypto. The App Coin is a powerful hybrid between economy, society, technology, law. As @iainc points out these are necessary expert ingredients necessary for creating a successful crypto the last ingredient being utility. In bitcoin this was creating an unprecedented efficiency between all of these ingredients with money. In crypto 2.0 it's about combining this efficiency with more specificity and flexibility.
As you say it is an experiment. Will App Coins continue to divide and multiply? Or will a few rise as the platforms that all the unique and desired utilities will be built upon. I am curious where it will go from here.