Sorry Luther sorry to say your answer is in fact incorrect
Root based watering depends on what it is.
Wicking and clay pot root based watering systems never over water plants. Both work on the soils natural wicking of water. So as plant takes up water natural processes replace the water. Wicking replicates what happens in soil with a high ground water level what all crop plants are in fact design to grow with.
There are some really expensive versions of wicking http://www.kisss.com.au/
The only risk with wicking is not over watering but under watering of items like rice and under watering that can lead to salt build up(this is normally fixed by once every 12 months to 5 year rainfall so 10 years no rain equals trouble).
Overhead, Driplines and old school under ground drip lines do all risk over watering and under watering.
Overhead watering in fact has many downside like increasing mould growth on particular plants.
Yes it true wicking based underground watering is not selective. So will water weeds as well as crop plants.
Sorry I am Australian so we have to live with the fact that we get dry times than could last 10 years on quite strict water restrictions. One of those is hand watering by watering can only at times. So farmbot overhead system would in fact break the rules when we are under water restrictions.
For research work were you are testing crop plants against different regional weather conditions the farmbots overhead watering makes sense. As a short cut to avoid having to remake the complete bed on a wicking design and attempting to get some level of effectiveness its also ok. The reality is something like a farmbot vs a well made wicking bed the difference is very steep. The wicking bed at worst %50 of the water overhead will for same result as long as you mulch the not cropped areas. Please do note carefully at worst if a wicking bed is using %50 of the water of overhead something is normally wrong it should be less normally this means you have a leak somewhere. Overhead can come even in water usage if wicking is losing too much from soil evaporation or have a leak. It basically in the point of impossible for overhead to win same with all the other techs not based around wicking with plants in soil.
The only thing that can best wicking in water effectiveness is something ponics like aquaponics/hydroponics… but this comes with a lot of costs and issues and design wrong will not perform. There are a lot of DPI studies in Australia on this as well as studies in Israel all coming to the same results. Australian DPI had made a machine for overhead watering a long time ago that watered based on when it saw green of plants this ended up being converted into a weed sprayer because it was found as not effective watering.
The watering side of farmbot I basically see as wrong. But when converting existing bed it is the simplest path. This comes purely down to effort people are going to put in.
As a crop development platform farmbot is right. This I think that is the problem. Some of farmbot design is more targeted at crop development lab work and the most effective crop production for water and power usage. So round peg square hole problem.