Music is music after all, so why go to the trouble of attempting to play the music differently, with different equipment? (For string players that means one of those funny pointy bow for starters.)
A very good question.
Something to do with the spirit of the music. The style of the music. The style that the music wants. The sound of the music. The feel of the music.
You know if you have caught the baroque bug because you just want to do it. The music begins to happen differently, to sound different, to move differently. It begins to move. The music begins to move you physically – as well as emotionally. It's a more physical, dynamic experience of music. A different experience. Being on a different plane.
As a string player, using a baroque style bow seems to be enough – if you persevere with it – to put you on the other side of the "tipping point", to make enough of a difference that there's no going back. I can still remember the moment the music (Vivaldi as it happens) began to dance in a way I'd never experienced before. And the bonus was that at that moment the music became easier to play. But what is the difference?
A clearer, cleaner sound. Poise and elegance. A certain centredness. Letting the dance spirit (don't forget that dance can be slow as well as fast) pervade the music. Shaping each note lovingly. Shaping each phrase lovingly. Certainly the bow helps with these things: maybe it's the sine qua non.
But is that it? Is a baroque bow all that's needed for the music to seem so much more alive?