It's not that Layout Variables are necessary to avoid workarounds, it's that the same exact thing can be achieved with very little effort and very little overhead, as compared to the effort needed by the developers to implement a feature such as this.
In other words, if you can easily do the task another way (and in this case, you can), then the feature being requested is pretty much useless, so why bother debating a whole new method of doing things? (Especially when the developers themselves have said "not bloody likely?")
Using a sprite, or even a text object, to store variables isn't hacky, it isn't cumbersome, it's not some outrageous or radical idea, and it would have just about zero impact on your game performance, so... what's the problem again?
It's all rather beside the point anyway since Aeal has already made a plugin that does this very thing, and actually has more functionality than Layout Variables because you can have more than one object per layout to store your variables in if you wanted to.
On the other hand, Aeal's plugin is a third party creation that not everyone is going to have, so it's just going to cause problems down the line if your .cap uses it and you need assistance in Help/Tech or something, because people will just be confused about why they can't run your .cap and then they'll have to go download the thing and install it and blah blah blah... or they just won't bother.
Long story short... there's not a single thing wrong with making a separate sprite or text object that stores certain variables for you, I do it all the time in my projects. It makes the whole concept of Layout Variables rather pointless if you think about it.