Sometimes doing your best is not good enough. Sometimes you must do what is required.
- “Churchill"
'… a number of incidents where take off has been rejected at or after V1 where carrying on would have led to a certain crash.''
Certainty' is word which requires careful use in aviation, and begs examples, open to different viewpoints, moderated by context, and supported with facts.
With one possible exception I cannot recall an aircraft which would have been unable to fly - even if investigations suggest otherwise.
'… and possibly a serious aerodynamic issue such as a flap asymmetry.'
All things are 'possible', but few actually happen. The safety requirements for flap asymmetry would involve a similar level of integrity as a wing falling off.
Instructors, simulator scenarios must temper what is chosen for example; it is easier impart dramatic mind numbing situations, than focus on the simple 'mistakes'.
Mis-set flap, incorrect speed, weight, thrust, or no flap with MEL alert. Real events, not RTO scenarios, but more likely 'off-the-end', 'unable-to-fly' situations where training, knowledge, discipline might help.