I'll welcome any alternative to Arduino IDE with open arms. I'm not sure why Arduino decided to reinvent a text editor instead of focusing on a plugin for a better text editor.
When new folks show up at the local makerspace the most common thing we encounter are people with no electronics and no coding experience. Their computer experience has been fairly non-technical up to then. Getting them up to speed on blinking a light already requires and intro to electronics and an intro to coding, kind of overwhelming for them to begin with. Requiring a "deep IT" dive to have extra editor-fu and installing toolchains etc would probably be too much, and we'd never get repeats.
Also worth noting: Arduino didn't invent their own IDE. They used an existing one - the same one that Processing uses. It's the wiring IDE/editor, so it was around prior to Arduino.
One of the surviving ideas was that this is an editor for beginners, to the point of having a smaller window was less intimidating, that it made the code seem like a sketch, and more encouraged playful experimentation.
This is my short, incomplete understanding of why the window is small when you open arduino/processing.
They didn't, they repurposed the editor developed for Processing ( https://processing.org/ ).
> instead of focusing on a plugin for a better text editor.
Which cross platform editor should they have focused on in 2005?