Editing a primitive's values AFTER initial placement first time posting in here so please forgive any protocol mishaps, I will try to adhere to the rules as much as possible!

So this is an often asked question and I'm not so sure how or why the absolute correct answer has never appeared. 

Is there a way to change the parameters of a primitive object once one has exited the initial pop-up window that appears bottom left upon placement of a primitive? 

Here are screenshots:





Apologies for the sacrilege, but in Cinema 4D, until you make the primitive editable, you can go back and change parameters way after initial placement:

!]3




As a switcher from Cinema, it's little things like this that can make the transition questionable initially. For all of the far superior mdelling tools in Blender 2.8 compared to Cinema, this is an essential oversight. Yes one can simply delete and start again, but that really shouldn't be part of the equation…

Thanks
No, you can't do that right now. Blender is a software that focus primarily on artistic rendering of complex scenes, and not much on motion graphics or other kinds of precise projects. That's why Blender doesn't have effectors or parametric objects, and why its modeling style is quite destructive.

Once you create an object, Blender sees it as a mesh, so a 3D model with a number of vertexes, edges and faces, so it doesn't know anymore if it is a cylinder or a sphere. This could change in the future, but I've heard Ton Roosendaal (Blender Foundation's Chairman) doesn't consider it a priority.

You can also check the answers of this similar question: How to edit Parameters for an Object after it is created?