It's recommended by people who used Nix for a while.
I have a different opinion myself though. While I don't use nix-env anymore I think it is important because serves as a bridge between nix and what people are typically expecting.
I think nix-env syntax should be improved to be similar what you expect with other package managers though.
Once you understand how nix operates you can then stop using nix-env.
I personally use nix for development. For every project I define the whole environment including all tools I need for development. This ensures that if someone needs to work on my project can get the same dev environment. If you add a tool like direnv to the mix it makes the experience much, much better, because then environment is automatically set up as soon as you enter the project directory.
I have a different opinion myself though. While I don't use nix-env anymore I think it is important because serves as a bridge between nix and what people are typically expecting.
I think nix-env syntax should be improved to be similar what you expect with other package managers though.
Once you understand how nix operates you can then stop using nix-env.
I personally use nix for development. For every project I define the whole environment including all tools I need for development. This ensures that if someone needs to work on my project can get the same dev environment. If you add a tool like direnv to the mix it makes the experience much, much better, because then environment is automatically set up as soon as you enter the project directory.