I know it's not quite what you want, but you could use node.status within a function node to show text and/or a variable so you could see what was going on.
Thanks @dynamicdave, status text is definitely something I use often in my designs, that is how I can see at a glance that the pump was running at 0% and consuming 5W in my original post.
node.status({text:`${speed}% @ ${pwr} watts`});
"Send to back" is mostly useful if you wish to hide a node behind another such as turning this:
into this:
but retaining the easy access to the function by moving the debug node into the background:
Just putting my 2 cents in the discussion.
I fear that one day the Node-RED Editor will became a heavy and complicated tool to use. I honestly think that a "Send to back" button tend to be a Feature Creep functionality since, in my opinion, that is not really necessary and it will make the flow file bigger and the editor harder to use.
One thing that makes me feel better is that the Editor is a package that is completely separated from the Engine, so maybe we will have 2 (or more) versions of the Editor in the future....who knows the future huh?!