The word “garden” suggests bespoke curation for appreciation and abundance, while “walled” suggests within this boundary the experience is purposefully tended and safe.
The Japanese put them in the middle of their homes. The British write children’s literature set in them. Just look — the very idea of a walled garden is lovely:
In film: https://i.pinimg.com/originals/5b/52/41/5b524125c48b35bfe0ca...
In life: https://en.wikipedia.org/wiki/Great_Maytham_Hall#Gardens
In my experiences with the non metaphorical variety, most anyone who can afford one prefers it.