My thoughts exactly.
Because the examples you cite are significant deviations with important consequences. Landing 15 feet off center will not cause a near miss with VFR traffic, loss of separation, CFIT or fuel exhaustion.
EDIT:
In my experience as an instructor(admittedly years ago), students who are lax with one aspect of airmanship, are lax with several others as well.
I think you're being overly alarmist. Again, you think landing 10' off center line on a 100' runway is unsafe, why would ever consider landing on a 50' runway?
EDIT:
Depends on the airplane, bad habits follow you from airplane to airplane. 10 feet off center on my current bird on a 100 foot wide runway is getting pretty close to the dirt, a Light airplane it is no factor. A bad habit will follow you to places and aircraft that are intolerant of the bad habit. (I.E. short and narrow runway or something bigger than a 182)
There are many operational differences between a 747 (or even a 737) and most light aircraft. The mark of a good pilot is noting all of those differences and determing what habits need to change. For example, I fly a 182 out of a 7000' field. I don't ever calculate takeoff or landing data. It's probably reckless that from day to day, I don't know whether my plane will need a 740' or 1100' ground roll. But it doesn't matter. I never verify gear down either. Were I flying a 747, I would change those habits.
EDIT:
If you refined the habit now, when it is easiest to do, there is no need to have to change the habit later. Trying to change later is how many many of those retractables end up on the belly.
Why are you resorting to personal attacks?