1155 was a proposal by the videogame/blockchain company Enjin to tokenize “gaming skins” and “commoditized items.” This is in contrast to the 721 standard that focuses on collectibles and one-offs.
So, what’s the point? Think about the company that proposed the contract- they are a gaming company. They focus on both ERC20 fungibles and ERC721 non-fungibles. If they spend so much time creating content that is based on both contracts, why not just create a contract that combines both and optimizes for that kind of mixed-use environment?
1155 allows entities to send batched NFT’s in a single transaction, which has allowed many developers to reduce their gas costs tremendously. This one dev, Philippe Castonguay, was able to save 80-90% on gas by using an 1155 method called Balance Packing. This reduces on-chain smart contract clutter by having one contract to manage multiple token types.
With the early internet, there was a war to figure out the winning protocol for data transfer across servers (TCP/IP). With the adoption of a single protocol, machines were able to communicate with new interfaces without having to conform to that machine's specific communication format. The same exists in the EVM- with different standardized norms, friction is reduced. With 1155, it further reduces the friction by allowing devs to not even think about what kind of token to deploy- just stick with 1155!