That is true but at the same time if play-testers already discovered that the game is better with either/or rather than both why should we go through the process of that same discovery. The scenarios seem to say either one or the other and while I am sure it is possible to combine everything together into one mega-arena....maybe there is a good design reason not to do so...
It's your game, play it how you want.
Maybe it isn't even a design issue but simply one of variety. If you always play with everything every time things might get somewhat samey.
What we really need is someone who was involved with the process to tell us what they found in playing the game in different ways so many times. What turned out to be most fun.
Of course...it is your game so..er...play it how you want.