I used the Time Aware app template for an app I created and I am really happy with it, especially the ability to add custom CSS. (I wish that more of the apps would have this feature.) I noticed that Time Aware is no longer available when choosing an AGOL app template.
I would like you to continue to support the Time Aware app template and also add it back to the Configurable Apps that are available when sharing a web map as an app. I know there is a time slider widget in the Web App Builder. By contrast, the Time Aware app has a different look, it is customizable via CSS, and works better for me on mobile devices. Also, the Web App Builder will not let you change the size or color of things such as the slider text that I can tell.