I think that we can, and have, all agreed that the cost of getting the PPL is a major entry burden to new pilots. As other have pointed out, that full-stop and taxi back adds up over the training period. Not to say the reflection time and pause in training is not beneficial but is it as beneficial as another look at the runway and all the skills learned through repetition to land well?
If getting the same amount of training over 40-45 hours was added to by another .3 you're really looking at another $2.5-3K for a license. At minimum wage here in MD for a young person that's another 295-300 hours of working to be able to afford that PPL and that's IF people do the license in 40-45 hours which seems increasingly rare.
In 1984 I started flying at 3FK, Frankling Flying field in Indiana. 2400x35 of suspicious pavement in Tomahawks. After solo at 10-ish hours I was out doing T&Gs solo there and at other similar strips. Perhaps not elegantly, and certainly sucking the seat cushion up some, but I was learning.
Fast forward to 2018 as the time money curves finally intersected again and I was went back to finish the private @ FDK. 5200x100 foot runway and we flew T&Gs with an instructor but you couldn't do them, along with frankly absurd wind limitations, solo. With the time from 1984 (and having accumulated a fair amount of SA in my NFO time) I was able to finish the private in minimal flight time and 4 months over the winter but I saw students flying the same 2-3 times a week as I did as their training stretched out. Mandatory phase checks, no T&Gs, wind limits, X/C wx limits. All the adds up as a cost and time burden.
Have we simply been driven to become too risk adverse? Flying can be a little dangerous (news flash) but not as dangerous as many things. We learn to stretch our skills through doing things over and over again and making small tweaks to improve both with an instructor in the plane and without.
T&G's dangerous? If you can't touch down on a standard airport runway, apply power, select flaps up, carb heat off (if needed) rotate and fly away (and put the gear up if needed) then I think perhaps you might want to consider some more time flying with or without an instructor. Do you need to do a T&G every time? Nope, in fact I routinely stop and taxi back after an instrument approach to set things up again and reorient myself. T&Gs are simply another flight maneuver in our range of things we do as Aviators.
I'm lucky. Still working but I have the time/money to fly mostly as I'd like but many many folks, especially the young ones coming into Aviation, do not. When I read people propose updates to the PPL standards like "we should have to do spins again", "We should mandate taildragger or glider time" or "PPL students need at least 10 hours of instrument" it just adds time/expense and may not significantly add to safety but certainly will keep many people from joining our ranks.
Certainly, the NTSB could give us stats on how many mishaps occur on a T&G evolution. Would they be able to give us how many T&Gs are done safely to come up with a ratio? As a former USN safety officer I can say with authority that safety is not our primary mission. Flying as safely as we can within our, and our equipments, limitations is the goal. If we want to be as safe as possible we would sit in a lawn chair and look at the plane in the hangar.
Just my 2 cents. Sorry for the thread drift.