The musician's earplugs that I have used usually were intended to tame down the volume of louder sounds while leaving quieter sounds less affected.  That wouldn't necessarily be a good thing in practice.  It could give you a less than correct idea of what effects differences in bow weight and speed and etc actually are having.

However, if you have a loud or particularly bright violin, and you are getting signs of way too much sound level for your ears' safety... Well, you may not have a choice. 

Just the way we hold and play the violin, usually the left ear is the most affected.  So other than the obvious sign of that ear (or even both) ringing after playing, there is also things seeming oddly a little more quiet after playing or your balance seeming a little worse for a while after a long practice session.  Those are major signs that you're exposing your ear(s) to way too much sound.  Damage can occur without any of those and without any noticeable pain, and that's why it is a good idea to talk to your doctor about regular hearing tests.

In any case though, I don't see offhand where either a mute or earplugs (musician or not) are likely to help with being able to tell what effect the bow weight and etc are having when you are practising your bow strokes.  I would think they will make it more challenging to hear the differences.