Yes, that’s a strange terminology that’s been used for ‘Convert Process to Global’. It doesn’t really define what you actually want to do.

I also agree on the redundant colours, which is why I find the new ‘Recent Colours’ addition pointless. I’m so glad you can switch that off!

I’m not holding out much hope for a further refinement. Most software developers are interested in upselling more additions to the workflow, not less. This is where AI not Ai!) would add value - by learning how you use the tools and adapt the software to help you become more efficient in your working practices.

When I need to add colors used on canvas as global swatches, I select the artwork, press New Swatch Group button at the bottom of the Swatches panel, and tick 'Convert Process to Global' option.
The name is confusing a bit, since it can be read as if the process colors were opposed to global ones... while these are not spot colors.
The method works, and the only downside is that it would add duplicates for already existed global colors — and these are immune to be found automatically with what Ai offers form the box.

The question though 'who needs non-global colors at all' is an interesting one :)
Again, I’m personally strictly against killing non-global as a thing. I’m pro to having an option to have global swatches as a default choice... but not enabled by default.

To answer — I don’t like having all the used colors in my panel. I want to keep only those colors there I care about and need to control.
I often use random colors on canvas I don’t care about. If I later choose to care about one, it becomes tricky, because Select Same commands are useless for both Fill and Stroke and can’t handle complex appearances.
The Recolor dialog doesn’t allow to convert a found color into a global swatch (there is a request about it — http://illustrator.uservoice.com/forums/333657/suggestions/40961173), it can’t actually change global colors (http://illustrator.uservoice.com/forums/333657/suggestions/43795632), and Find/Replace Color (InD style) doesn’t exist (http://illustrator.uservoice.com/forums/333657/suggestions/46591144). So many problems...
So I use different ways to solve it when it comes, including Magic Wand and scripts (specifically this one — https://github.com/creold/illustrator-scripts/blob/master/md/Select.md#selectbyswatches)

Hmm, it’s still not an answer, right? :)
I don’t have another though!

Here’s an example of Ai not retaining Global colour information. An asset supplied by my client does not show the colours in the swatch list options. When I select the blue and drag it into my colour list, Global is switched off. I have to select it and manually change the setting. I’m wondering why we have the option to switch Global on or off anyway - is there a reason people would not use it? I’ve been using Ai since v7 and never not needed Global for my workflow.

Like InDesign, all swatches are global by default.

I still don’t get how do you create swatches.
If you drag (you say you drag) colored objects into Swatches, a pattern swatch is created... not swatches.

And no, making global swatches by default is not what is to be a universally desired method :) I agree there should be an option to toggle this, but please don’t think that everyone wants to create global swatches by default. I personally prefer globals, that’s true :)

The idea about a 'global switch for globals' is a good idea! Perhaps a script can be made to do that until the team makes one...

I work in numerous ways - I create my own assets but also edit client files and import PDF pages to edit or extract elements from. I also cut/paste across various projects I'm designing. When selecting items from other parties documents and dragging the colours into the swatch palette they do not assign Global colours - I have to double-click the colour and manually assign a Global option before it becomes flexible enough to edit. I am wondering why there is an option in the first place - if you are working with colours, as you do in InDesign, surely it would be best to just make everything Global as default, to make it easier to edit? Why do you need instances where a colour you're using is non-Global?