The UI is very much a work in progress at the moment, and you can see we're still improving it in Alpha 12. You can expect a lot more work to be done on the UI front in the future.
One thing that we would like to improve is the handling of the locks, and some better solutions for balancing simulation vs you being able to enter anything you'd like.
For instance, if you have a body and you set the temperature, unless it's got some mechanism to keep it warm, it will naturally cool. Or, if you define a body's radius as too small, it would naturally expand until it reaches an equilibrium, and change the density along the way. We need a mechanism where you can say, (stop simulating this specific element), or allow you to rescale parameters and still have the simulation react in some fashion.
We've been discussing how best to handle this, and if you've got some recommendations, we'd be glad to hear them as well.
Long story short, we're working on it, but it might be a while till we settle on a solution we're happy with.