Hi,
i think there are something to point out on this...metronome can help everybody improving the self sense of rhythm. Rhythm and syncronicity it is a major stone in music, music first is rhythm after we can find melody, harmony (what we call for), sounds, dynamics, colours and so on.
Rhythm itself create the music, oscillations are the origin of both sounds and rhythm.
First of all the metronome provide you a "mirror" on what you are doing with your body, who practiced intensively with metronome start understanding how his muscle and how his brain and how his attitudes affect the music, sometimes in some hard passages you feel surprised on how you rush on, you accelerate on difficult passages (instead of going slow), this is a result of an audio-motorial feedback reaction but without the metronome you cannot have a minimum idea of this. And this is very important to develop a relaxed expression and to identify tensions directly for an aural feedback.
As we play bass metronome is more useful for us because bass is mostly the roots of the musica building and have deep roots in rythm and pulsation to offer to other player with secure strengh.
Another important is that, apart when you play alone, the metronome teach you in the best way to play with others, to play with an external reference.
Plus, the metronome teach you to help your brain to keep listen the others, you need to always listen whan you play and play is first af all listening, you cannot play like a machine-robot alone in the space, you need to listen, better you listen better you play.
Plus the metronome help you to have the "memory" of the pulsation, as a reference, you just setup a tempo, start the metronome and after a while you stop it, you start to play and at the end you will compare your speed with the metronome, he will give you important information if you have tendencies to accelerate or to slow down o certain tempo.
Again, the metronome help you to open your mind in association between aural patterns, changing the position of the tik tok inside the bars allow your brain to shift rhythmically between aural pattern and thank to this you will become more and more indipendent on sounds patterns that your brain is associating to rythm. For who know jazz: how we have deep in our brain the hihat on 2 and 4 of any bar.
Again, polirhythm, adding polythythm feeling inside you make the music more rich, also if you play the same even 4/4 things, the result is more brillant. if you set for example the metronome on the second beat of a triplet and you play on even rhythm you can absorb polyrhythm feeling inside your body.
Another: we live more and more alone and we play more and more alone, this happens often in big cities where people dont play toghether so often and where we cannot play on the streets as century ago, the metronome will help to have a "reference" on what we are doing also when we are alone, nobody can say "hey you are going to slow down too much here!", the metronome can tell us a lot through our ears, just listening.
I think that western classical academic approach to music attempted (since decades) to exclude dance and rhythm from the process of making music, in fact it is a post colonial cultural behavior way to exclude Africa and all other countries: so lot of classical musicians think that the metronome is not necessary or is like a "robot-monster-machine-that-make-you-a-monster" when in fact if you hear how they play it is the opposite. You need to discover the mechanical monsters inside you if you want to to play fluent and free and swinging like an angel and a metronome help you to do this otherwise you thik that you can but its not for real.
This is what i think on metronome.
End for real: when i improvise with other musicians i can feel their rythm strenghtness or weakness and when i notice that often i ask if they practice with metronome (or recordings, is the same), and always i have the same feedback, people accustomed to play alone in their room w/o metronome they dont listen at you, they continue to play out of tempo or loosing immediately as you do some tricky stuff. Maybe they have a great technique and they can read very fast very difficult things but making music it is another story.
Ciao from Rome, Italy.