I wouldnt make this an issue of 'training' for the event that autobrake doesnt do its job. In my opinion thats like saying that "I dont want anti lock brakes and traction control on my car because I will otherwise not know how to accelerate gently and how to use cadence braking if the road is slippery. Every aircraft tends to feel slightly different, each runway surface is different, each set of tyres is different. Autobrake (up to a certain level) aims for a set deceleration rate, when it cant reach it with the maximum brake pressure for the setting youre probably not using enough reverser or the runway is slippery. Yeah, on a three kilometer runway you'll probably fine with 'autobrake off' - even without any wheel braking at all and idle reverse if youre okay with vacating at the end, but why would you? From what I have witnessed people tend to increase brake pressure as they slow down because that intersection they were planning for suddenly comes closer and closer, not comfortable for the pax, can't be great for the brakes either. Autobrake gives you a ballpark figure for rollout distance that you can ensure with reverse thrust if necessary.
BUT - from what I understand, if youre using carbon brakes, proper manual braking techniques (push the brakes and keep'em there) can increase service life and reduce heating greatly since autobrake might rapidly modulate... Not a black and white issue as usual.