Board Game Arena

There should be a checkbox to opt out of turn based games. Otherwise creating games takes several more clicks.

there is such a checkbox

As Kurosawa noted, there is a checkbox. At least for viewing games.

As far as creating games, which is what you mention, the only difference is which item from the game speed menu you select. As the site defaults to the last selection the player made when creating a new table of the same game, this is at most one click more than the general default behavior. Also, with turn-based, once the maximum number of players have joined the game, the game automatically starts. This saves the creator/administrator a click of the "start game" button.

So, what are the "several more" clicks needed that your proposed change would save?

I don't get that either. As far as I know, it's only about the speed you choose, and you have to do that on real-time ones anyway.