Just curious - it used to be super simple to make little css changes like submit button background colors, but now none of the old selectors work. My question is, what is the benefit of changing to the “Orbital” theme when it now takes so much longet to find a css selector and change it? What is the upside of this change?
I don’t work for Gravity Forms, but at the heart of the new Orbital theme is CSS variables. Where CSS variables shine is creating “themes”, and I suspect “Orbital” is just the first of many themes that will become available in the future (don’t hold me to that though 
).
To give you a practical example, take a look at this recent forum post: Styling the submit button
The first reply uses the old way of styling a form, which requires tracking down all required selectors and then overriding them. The second reply (mine) uses three CSS variables to apply a new “theme” to the form. Gravity Forms documentation could certainly be improved in this area, but I know which method I prefer.