Why aggregating transactions into blocks?
The Problem is that the nodes in the peer to peer network need to synchronize after every block. That means every new block needs to be shared with every participant in the network. This takes some time.
If someone on the other side of the world creates a block it might take a few seconds until this block reaches you. Even if this block contains only 1 tx. That's because latency does not reduce, if you reduce the block size.
Therefore you would have to give the network at least a few seconds time to synchronize after every transaction. This would reduce the overall tx per second drastically compared to aggregating multiple tx in a block and producing a block every 10 minutes on average.