Explain why the Greeks might not have had a great influence on the world if they had better farmland?

The Greeks would not have much influence in the world if they had larger areas of good soil and cropland in their area for agriculture. Only a small percent, around 20% of its land was usable for growing crops (most of them were grapes, barley, and olives). Because of this, they feel the need to mix with other communities in search of better and more agrarian lands for their development. Soon their social, political and economic organizations would be highly changed and Greek style would influence the world.

If the Greeks hadn't had the not-so-good geographical characteristics they have, maybe they also wouldn't have had the great influence on the world they did have.

The access to good farmland was primely important in ancient times because it was all that the people had to work with, in order to eat or build. As they didn't have the best farmland in the Mediterranean shores, they had two options: trading, which wasn't very useful if you had nothing to trade with; or going for some fields outside their own.

In this pursuit of this economic independence and growth, the Greeks started to colonize tha lands around them, thus creating a several-centuries-lasting Empire that put them at the top of cultural and political developments.

To summarize, their lack of perfect farmland is what forced them to look for and discover new possibilities, and some of their discoveries survived till our days.