[Gorkys]

To my mind, all of the points you listed as an advantage you can also find with C#/VB.net using WinForms. I've also never found WinForms or even WPF (most of the time) to be sluggish on even reasonably modern hardware.

What specifically do you find easier in VB6 than VB.net/C# when writing desktop apps, in particular in relation to WinForms?

You say "inspect and modify a program as it is running in a graphical way" - do you mean that with VB6 you could alter the UI as the application was running? If so, that's something I don't remember but I agree it could be very handy!