My interpretation of the Season 1 Vok events was that they seeded the planet with energon and built the standing stones for some undisclosed reason. Then when the Maximals investigated the standing stones, their fight with the Predacons set off the signal that brought forth the alien pod that absorbed Optimus Primal to study him, for the purpose of enabling the Vok to learn about these new unforeseen elements that had come to the planet.
In response to the discovery of the Maximals' and Predacons' presence on the planet, the Vok then created the flying island as a sanctuary for the foreign newcomers to reside (as Tigatron put it) "in peace," still near the planet but physically separated from it so that these foreign objects could still be around while being taken out of the experiment's territory.
However, though the island was perfectly equipped both to sustain the Maximals and Predacons and to forcefully keep them in check with the obelisk's swift and decisive form of discipline, the Vok hadn't anticipated the Predacons' (specifically Blackarachnia's) craftiness and ambition, which led to the island being turned from a safe haven into a weapon of mass destruction. With Tigatron forced to reluctantly destroy the paradise that he had so wished to maintain, the last bout of power in the obelisk sent its final signal back to the Vok, alerting them of the island's destruction at the hands of those it was made for.
Understandably, the Vok didn't take kindly to what they perceived as having been a gift given out of mercy and generosity being practically thrown in the trash by its recipients, and concluded that these intruders were no longer worth saving, for they had not only rejected the Vok's hospitable gift but their conflict had done enough damage to the Vok's experiment for them to deem it unsalvageable. Thus, they decided to wipe the slate clean, putting an end to their failed experiment and those whose cancerous interference had ruined it.
Edited by Sabrblade, 03 January 2019 - 11:38 PM.