Deeper means better root for beginners. Structurally, certain deep postures automatically align you better with gravity - so it seems 'natural' that this means there is an automatic correlation between deep stances and 'rootedness.'
Which there both is and isn't. As your training advances, you learn to maintain 'rootedness' even when upright - and it the actions of force upon you or an action you are taken that determines the 'direction' of rootedness.
Being able to sustain this feeling into reality means coordinating your structure, breath, mind, in a plethora of different ways. I make no bones about being out of shape due to my work responsibilities, yet this 'root' gives me a strength that is deceiving compared to how I look right now.
In my school, 'root' is not to be confused with compression. Boxers, FWIW don't have 'root' in the same sense - at least not on purpose. Compression does take advantage of the root path, but is not 'rootedness' - at least how my school defines it.
Then you need to consider substantia and insubstantial. Personally, I'm a big beleiver in footwork to control distance. Wether you wait and bait, or dance and confuse depends more on your oponnent than on your personal reference. But from my experience, you can maintain 'structural alignment' without having to be fully 'rooted.' - nor is it always advantageous to be so.
I'm splitting hairs here, so i hope it makes sense...