Running analysis in the ArcGIS Online Map Viewer is often perceived to be slow due to the fact that a new feature service is created to host the result. Hence, there will be very little time difference when e.g. running a buffer analysis for one point vs a thousand points. Since a simple analysis often takes a minute or to it doesn't facilitate explorative analysis or spark the curiosity to test new tools or approaches.
To solve this it would be nice with an option to only return a graphics layer as an analysis result. This would be very quick as no hosted feature service is needed. This means it would be both easy and efficient to test different tools and approaches to solve a problem before settling on a final analysis workflow.
As a logical next step it would be great to then be able to save an analysis result graphic layer as a new hosted feature service. Then you would not have to run the analysis again to be able to store and use the analysis result data outside of the web map.