Flash/Silverlight/HTML5/WASM - this, to me, is a story of a technology being useful, then growing to give too much power to web publishers - who tend to abuse any given power - then reverting to a weaker technology in order to unscrew the web. Rinse, repeat - HTML5 is already rapidly approaching peak Flash, and introduction of WASM isn't going to help here.
Soap/REST/JSON API - you could call it a story of simplification, but I don't get how it even came to be. That is, how XML gained so much popularity, given that simpler and better tools for almost all of its uses were already available and known.