If it does that while the crew is distracted (why else would they forget the gear) you're putting them in an unstable situation, close to the ground, descending rapidly.
The current warning is fine. After what this crew got, if you still continue, it will literally shout "too low, gear!" at you in a continuous loop.
Landing with gear up happens sometimes, and pilots are supposed to do a decent job with it. Large passenger jets have done this and been put back into service after repairs.
Failure can be detected. Throttle up, and any other needed adjustments, can be done immediately by the computer. Getting up off the runway again can be automatic.
Aviation is not the type of industry where "failures can be handled automatically by the computer" is an acceptable answer. There's almost always manual systems in place for when the computers fail, which they do.
[1] https://aviation.stackexchange.com/questions/16913/if-the-la...