>I couldn't understand the fascination with the integrated environments though
That's one of the key benefits: the environment is an object too.
First class IDE knowledge about your objects (Smalltalk pioneered automatic refactorings etc), the ability to modify it as you like, hot code reload, re-startable apps, "live" images to send for debug, etc.
It feels like an alien world moving into the Smalltalk live environments and the patterns I've built up over the years and tools like Vim, etc are indispensable when it comes to moving around and modifying code. Of all the reading I've done on it, the entirety of the language is contained inside images. I know that the Pharo guys have engineered this marvel, and I think it's on the verge of a breakthrough with a lot of people if they can ease into it somehow.
It is an alien world.... but a better one by most measures.
I come from Emacs (20+ years when I first encountered the Smalltalk IDE), and find aspects of code editing irritating sometimes, but the overall value of the IDE more than pays for that irritation.
One of the coolest things is TDD carried to an extreme level. I build my test, and it fails because there's no such method, so I get a debug window and tell it to create the method... then I fill in the contents and click proceed... and picks up where it left off! It either works, or I'm back in a debug window fixing what failed. Total time from thinking of a test to working code, often less than 5-10 minutes.
(Joking of course, but there's no reason a Smalltalk environment could have a Vim-behave-alike editor, but even better, e.g. with semantic knowledge of the code instead of just words and chars).
That's one of the key benefits: the environment is an object too.
First class IDE knowledge about your objects (Smalltalk pioneered automatic refactorings etc), the ability to modify it as you like, hot code reload, re-startable apps, "live" images to send for debug, etc.