I'd like to see a more discoverable, and more, UI for Rails generators. For example, instead of having to find Run Rails Generator under Tools, a more discoverable "Add Model" command would be great. The UI would have a field for model name, and the columns would be added individually, with their types in a pull-down. Ditto for migrations, new app, etc.
I realize that there are a lot of generators, and so having the general "Run Rails Generator" is still useful. But it's really just a modal for the command line, with a bit of autocomplete. Rails is designed around the command line, of course, but embracing the more popular Rails concepts in the UI would be friendlier.