The closer you are to drafting the entire cube, the more players will be able to "go deep" into dedicated deck archetypes. If you draft less of the cube, there's more variance in whether your support cards show up or not, so going deep is riskier, so the generic goodstuff strategy becomes stronger.
You can also simply draft more cards per person to compensate, but that can affect the overall power level (which defeats the point of the cube to showcase cards underpowered in constructed). And the point @SneakySly just made while I was typing this up... the beauty of cube is that any way you choose to configure it, you will have an interesting draft
Edit to add: I would personally prefer drafting 240 for 4 people since I also like when the cube is closer to 1x of most cards than 2x or 3x (with the exception of special cards like scorched earth and biotic labor).