Well, I'm new to Elements so I don't know any existing backstory behind the pillars, but, I was imagining them as focuses for elemental power, like a place where that power could collect and be used.
I see Entropy as the element of raw quanta. With Nova and Supernova in the fold, entropy seemed like a natural place to begin tapping random quanta. Then I had to choose an element that would create the pillars. That was either going to be Life as a source of creation or Earth as a source of matter. I choose to go with Life over Earth.
If that combo is frowned upon I could change it to Earth or even Mono-Entropy, but, up the cost in that case.
(plus, in my rainbow deck Life is next to useless, my pile of Life quanta always seems to grow faster than the rest, having a sink for it like this seemed like a good idea to me.)