#1 issue with applets was integration. Was it on the browser? Which version? How does auto-update work? etc. Adobe did an amazing job of making sure Flash was

#1 issue with applets was integration. Was it on the browser? Which version? How does auto-update work? etc. Adobe did an amazing job of making sure Flash was there, and seamless. To the point people barely had an awareness. Java Applets failed because Sun was a 'debating society' (per James Gosling). Definitely not a consumer oriented company, thinking about end user behaviour etc.. Other reasons as well, but that's #1. Source: me, deployed a bunch of Enterprise projects on Applets back in the day.