There is no virtue in using less memory for the sake of it. If a desktop application is taking 100mb, you can have a lot of those running before modern boxes start to struggle.
* 32-bit vs 64-bit application(64 bit will bloat all pointers)
* Methods of loading and editing documents(modern editing attempts a lot of introspection based on highlighting syntax or project environment)
* Character encoding support(Supporting current Unicode rendering would almost immediately take you beyond 4Mb)
Interactive editing is a pretty memory-hungry task compared to a simple viewer or batch processor. There's more reason to keep things cached. If you actually go back to old text editor versions from the days of 4Mb desktops, you'll find yourself missing stuff. Not so much that you can't get by, but enough to give pause and consider taking the hit.
You know... any embedded programmer reading that comment is probably laughing hysterically. In most cheap or energy efficient microcontrolers, more than 4 Mb is considered a luxury.