Mining is a race.

Miners work together making pools, trying to solve proof of work algorithm before the others.
When a miner finds the solution (the hash), this solution is broadcasted to all nodes and a new block is created.

The difficult is automatically adjusted by the protocol every 2016 blocks (about2 weeks), so that the average block time is 10 minutes.
If miners go too fast, difficult goes up. If they go too slow, difficult goes down.

Reducing difficult would reduce blocktime, breaking the race completetly. THere would be thousand of miners finding blocks at the same time and broadcasting their solutions. There would be a lot of orphan blocks and involuntary forks.

The system works like this so it can work. the difficulty is high not because the network wants to harm small miners who use personal computers. The difficult is high because there are a lot of people mining, and professionally mining.