I've already implemented my own way to customize the parsys new area text that usually says Drag components here (touch ui) or Drag components or assets here (classic ui). It's very helpful for the authors in big corporate websites where there might be many paragraph systems and stuff gets confusing. The configuration from developer point of view is as simple as adding a single entry into the designs file just as described here. I've seen posts where this can be done by adding new containers for each case where a custom text is desired. But with my approach I can reuse the same parsys everywhere and only configure one aspect for it, not being forced to add new component types each time for such case.
My question would then be like that: am I missing something that's already there? Is there an out-of-the-box way to do so? If there's not any - why not? And will it ever be introduced and implemented? Inspectable.js will be droppped in the future (a comment inside of it says so), so my approach will need to be changed and it might need an update each time the AEM version goes up...
I am not aware of any ootb way of changing the text without developing custom code as you specified in your article.
With AEM - providing custom code is required sometimes, When developing custom code - its also a developers responsibility to refactor the code to ensure it works with an updated version. Typically you need to add new dependencies, etc.
Also - the default text - Drag Components Here is not an issue for most developers - most likely why AEM Eng will not change it.
Providing custom code is a general thing required for any framework/system/CMS if one needs custom results (and configuration does not allow it), AEM is not special in this matter. The same applies to the necessity of adjusting custom code to new versions of the base software.
Indeed the Drag components here text does not matter to a developer so much, but it does to a content author and that's why I've seen efforts to customize it in a couple of projects. Fortunately it's not that difficult to override, but still it would be nice to have it OOTB. But well - if AEM Eng will not change it - let it be.