Dairyground,
Simple solutions may have merit, but they have to demonstrate practicality and reliability; if not they may make the situation worse.
What margin of time should be considered to allow for variations in wind-speed, change in crosswind, variations in runway condition, runway texture, tyre effects. What margin is there in setting and reading the clock?
Say an accumulative 2 sec. Even in my old puffer jet with a 20 sec ground roll – to V1 or more, 2 sec is 10%; can we afford that 10% of take-offs might fall into a possible RTO category, with associated hazards?
Timing is fixing an outcome, this is reactive safety; the industry has to understand the cause so that proactive safety measures can be found – avoid, prevent, not mitigate in critical flight phases.