I'd say this post provides an excellent summary.

There are gliders where, to obtain improved performance, it is sometimes
helpful to fly uncoordinated. For example, to persuade my Open Cirrus
(1967 design, 17.7m span) to turn into a strong thermal, it's sometimes
most effective to yaw it towards the thermal enough to induce the
beginning of a wing drop - then catch it and continue into the turn.

BUT, this is deliberate uncoordinated flying. If you haven't been taught
to fly coordinated, you won't be able to recognise when and where it's
safe to do the opposite.

In the circuit, or thermalling low down, I work really hard to keep my
turns coordinated. Attempting to turn in the way I described above would
be a recipe for disaster. I only do it in the circumstances I described
because I was TAUGHT to fly coordinated, and now have enough experience
(I hope) to recognise when it's safe to do something else. The default
should always be coordinated flying.

user wrote:
Bad habits don't discriminate based on titles. Sadly, titles can more easily
pass on those bad habits as best practices. The rudder first approach is
something gleaned by many pilots from the stories about a few marginally
controllable "super gliders" from a previous generation of the sport. Its
reapplication to certain "underruddered" two-place training gliders shows a
remarkable lack of understanding of coordination.

Here's the crux of the problem... the rudder first approach is most
effective at low speed, when the ailerons produce the greatest adverse yaw
and the vertical stabilizer has less righting force. When is coordination
most important?

To make your argument I'd focus on the following:

Lack of coordination is universally discouraged. Any training regimen which
promotes lack of coordination needs to justify it based on both increased
controllability AND uncompromised safety.

Generally, all sailplanes require more rudder with less aileron at low speed
to remain coordinated. Shouldn't pilots be taught to discern the difference
in control effectiveness throughout the speed range rather than to simply
using an expedient that "works" in one case?

If you teach someone from the outset to lead with rudder, isn't it likely he
will continue this practice for ALL aircraft and in all conditions?

Modern aircraft are built to standards of controllability. Does your model's
operator's manual suggest leading with the rudder? If not, why not?

And finally, from an aesthetic point of view, it's just plain sloppy. As a
CFI, I'd question the abilities of a pilot who couldn't make a coordinated
turn in a modern glider (SGS 2-33 included) all the way down to MCA. Slewing
the nose before banking... every time you turn? My comment to the pilot
would be to fly the glider you're in, not the one you're fantasizing about.

;-)