Thank you. The button was a user request. The rationale is that most users would not use the UI so it would not take up space. Now that pagination is introduced, this is less of an issue but is still a point to consider.
In the general case, a theme can show many full articles in one page (think one-page themes for example). As the UI reuses observables, only one UI can be open at any one time. Therefore, in the general case, the button, when clicked, closes all other similar UIs and then opens its own UI.
For this reason, I cannot provide an option on whether you want all UIs to initialize as open. The best I can do is add an option which, when checked, would open the first tipping UI on the page. In the next release I will add an option that does this when enabled: