I suppose one reason is that images can be stored in many different ways in memory. For OpenCV images in C++ the Visual Studio extension Image Watch is quite nice, I think it's been around for more than 15 years:

https://marketplace.visualstudio.com/items?itemName=VisualCP...

There's also a recent extension called Image Preview for path references:

https://devblogs.microsoft.com/visualstudio/working-with-ima...