That's a valuable reason to have strong keyboard bindings. But there are many circumstances in which it is helpful and valuable to be in a state of float, observing your environment while allowing it to operate upon you until the merit of one direction clearly predominates over others.
This is how tiny bacteria with flagella operate; they whip their hairs furiously when they want to zoom towards or away from a particular stimulus, but tumble idly in intermediate zones. Having only one mode of operation isn't adaptive.
Definitely. There are advantages to both states, as they're optimized for different things. There are times for information gathering and eventually decision making, and there's times for acting on those decisions. While neither is generally a state of purely that type, there are reasons to believe that the optimal tools for one may not be the same as the optimal tools for another.
In that respect it's not whether keyboard binding or mouse context menues are better, it's about providing tools to support both contexts, so the appropriate one can be chosen at the appropriate time.
FWIW, UX research (perhaps in the 1980s) also suggested that while many people reported "feeling faster" with particular input/editing actions (compared to e.g. using a mouse), in some case the operations were no faster as observed, but they apparently involved enough cognitive load to produce a time blindness in the user.
This is how tiny bacteria with flagella operate; they whip their hairs furiously when they want to zoom towards or away from a particular stimulus, but tumble idly in intermediate zones. Having only one mode of operation isn't adaptive.