Solutions are great way to refresh dependencies and to deploy to another environment, and on our project we use them often. But maintaining them is not easy. I think some improvements would be great:
1. Possibility to clone a solution - if you need to have another one with few components removed or added, but don't want to add everything from scratch.
2. Possibility to associate many components at once. Ideally to have a list of all modules where you can check/uncheck them. This will be so much better than current auto-complete to add only one (with waiting for submit to reload the page).
3. Automatic read-only solution with all user modules (no system components), which you can publish, create version and download as normal.