I’m a native Japanese speaker, so you don’t need to explain that writing kana with spaces is non-standard in most media (although some people -- both native speakers and non-natives -- erroneously claim that no native media uses that form of writing).

The people at Kanamoji Kai (all native speakers) are well aware of this too, and their website even has a section on 分かち書き (word separation). They use the example スモモ モ モモ、モモ モ モモ、モモ ニ モ イロイロ アル。 to illustrate that using spaces is a must if we switch to kana-based writing.

>> these full kana games would be harder even for natives if they used a more standard space-free style

This is true, but I take issue with your use of the word “more standard,” as USING SPACES IS THE STANDARD in full kana games.

Any form of writing reform, by definition, involves moving from the current standard to something that is initially non-standard, right? Korea got rid of kanji and now uses spaces with Hangul. In my opinion, it’s way easier to adapt than most people think.