I am not familiar with the specifics of bonsai trees, but in general plants need to maintain a ratio of roots to leaf area in order to stay healthy. Also, your assumption that the roots take in water and nutrients at the tips only applies to woody roots and even that is not entirely accurate. You can not take anecdotal evidence to erroneously make large assumptions of biological concepts especially when those concepts have been adequately analyzed decades if not centuries ago...

The currently held theory for how water flows up and throughout a plant was thought up and researched over 110 years ago... Dixon, H; Joly (1894). "On the ascent of sap". Ann. Bot. 8: 468–470.

Maybe it's just a conflict of personal philosophy, but I desire to teach people the applicable scientific concepts behind aquaponics so they can decide and figure things out for themselves. As the saying goes, if you give a man a fish you feed him for a day, if you teach a man to grow fish in an inexpensive and low maintenance aquaponic system you feed him for life!