We need higher difficulty to reduce the amount each miner is getting
.
You misunderstand what the difficulty means.
If you increase the total hashing rate blocks would be generated faster and faster.
To counteract this the difficulty increases.
There are more and more miners (machines, not necessarily new entities) working on solving blocks.
Difficulty is there so the amount of bitcoins mined stays roughly the same no matter how high the hashrate is.
Because currently the hashrate is growing quite fast block emission times on average are actually a bit shorter than they should be.
The reason for this is that the difficulty re-targets after 2016 blocks. Simply put, if a miner goes online right after a difficulty re-target
there is more hashing power than anticipated so blocks are, on average, being solved faster than they should be.