I pretty much do? I definitely have some strong personal biases toward particular instruments and not others and I would push for those. Asking a kid to choose a music instrument yields a decision every bit as informed as rolling a dice. Why bother?
It's not like there is an objective way to choose a "better" instrument anyway since half of the fun is playing with others who use different instruments.
Why would it affect their development if they picked say a trumpet, guitar or flute instead? They can always pick up a different instrument later.
It would be like if a kid wanted to learn python and you said "no! you must learn Java instead".
EDIT: Setting aside the above argument for a second, there are practical considerations too that make the choice of musical instrument a non-arbitrary decision. For example: the cost of the instrument, its portability (important if the band decides to tour) and of course the availability of instruction.
Except that is his own decision.
> Why bother?
Because a kid is a separate person, not an extension of your personality.
The relationship between a parent and child is not a democratic one. As a parent you have a responsibility to make choices for your child until they can make them for themselves. I do not agree with letting kids decide which developmental activities they will or will not partake in or how they will do so. Is that clear enough for you, sunshine?