I think it's a great idea. I'm not sure that the average person understands what an asset is and how it works, so having a simple concept like this one will help them understand the basics of investing in assets. Go to this https://masterbundles.com/best-free-shopify-minimal-themes/ site to download beautiful blog templates. I think it's a good idea to have these themes available, because it makes it easier for people to learn about investing. The more basic we can make investing seem, the better off we are as a society.

I would like this feature developed as well, although it would probably make more sense to make a brand new color management tool for XD, Ai, Ps and the CC libraries that takes advantage of current features already existing.

We basically need Layer comps, like in PS (which are already supported as a variable property for smart objects), and we need global color groups that can be dumped into a CC library and switched with one another, much like in the recolor tool in Ai. (Adobe Color already supports the creation of themes that can be used in recolor, but it has limitations, only 5 colors, also to my knowledge you can't put Ai color groups in the CC library, yet, probably because nothing else can read them at the current time)

In a layer comp, I should be able to express which color group is active in an artboard, as well as define show / hide status and position for objects. This way you could partially solve the problem of micro animations too.

Let's say that I want to show how a drop down menu looks, I make a layer comp with the menu collapsed and one where it's not and link them.
It has some limitations, but XD is also a tool for prototyping, we shouldn't aim toward too much animation options.

A requirement that I see often is to allow the user to choose view options, including dark or light. Having the ability to duplicate a palette that would allow the user to see the different “Theme” options within a prototype would be EXTREMELY helpful. I have attached an idea about what I was thinking...

I like to offer color theme options, or even to let the user choose their theme.

Doing this is easy when I work in Wix, for example. I start off choosing a color palatte/scheme. Then after I design, I can easily change the scheme of the whole design by switching between palattes. So, for example, everything that I made light-blue on palatte1 becomes yellow on pallate2.

It would means that light/dark colors on palatte1 stay light or dark. For example, yellow can become pink, light blue, light gray, etc...but not dark blue or gray.