Like most of the performance and handling qualities regulations, the
conditions under which Vmcg is determined is a scenario intended to provide
a high level of safety for a wide range of conditions. An alternative
could be to require manufacturers to analyze each particular
condition/event that may occur, assess conditional probabilities, etc. and
determine Vmcg from such a detailed analysis based on a specific safety
level criterion. Instead, the basis of the current requirement is that
by determining Vmcg to be the speed at which, if the critical engine suddenly
fails, and limited the resulting runway tracking deviation to 30 feet
using only the rudder to control the deviation, and including other
conservatisms, a wide range of conditions/events are covered.
For the 757 on a standard 150 ft width runway, the 30 foot deviation requirement
leaves an additional 33 feet to the runway edge. In the operational situation,
the nose wheel will take side loads as well as provide some steering
capability, which adds quite a bit more directional control authority.
If not runway length limited, differential braking can also be used.
But on that day when you are at aft cg on a narrow, short, slippery runway
with strong crosswinds, and you have a sudden engine failure just before
V1 on one of your spanking new engines that are putting out more than the
specification thrust, and your nose wheel steering linkage fails, well you are outside of the certification requirements.
More directly to your question of just considering a strong crosswind, I agree that it would be prudent to use higher than the minimum V1 if that option is available.
Mearse