It's all about scalability (although there are some things to improve stability).

The major problem with eth is that it doesn't scale well.
What that means is that the more people use the network, the slower and more expensive it becomes.
In 2017, the problems really started to show.
For example, there was a very popular game called Cryptokitties.
It was like Tamagotchi and Pokemon but on the eth network.
It caused a huge spike in eth network traffic and confirmation times slowed down to hours and gas prices soared.

The upcoming developments are meant to fix this.
People are excited because this keeps eth competitive against the newer smart contract platforms and shows eth has reliable development.