Expressing the music is the exact reason I prefer on 2. That remains the case in shines.
But you do what works for you.
On2 in dancing specifically refers to breaking on count 2 (and count 6). That is change of direction (in son too). It accents the upbeats. Unless you mean something else. How according to do you do shines on2 work exactly. In most of the classes and workshops shines are choreographed. Shines are not only about footwork. Body movement and arms also get used to accent music while the feet might be marking the beats. You can’t willy nilly do shines learnt in the class to any music. Because when you learn them in the class, they were set to specific music phrase from a song.
You can accent multiple things in the music when doing the shines. You can accent the beat you want, the clave, a particular instrument, a melody line, etc.
During the live music set, the best part to shines is during percurrsion heavy parts. You are doing footwork to the percussion hits more than anything else. If I change the direction on the count 1 and hit the count 2 (accent it with some movement) is that shine on2 or on1? Accenting the beat when shining can be done in many different ways using different parts of the body.
Hence classifying shines as on1 or on2 is only a teaching tool and not an actual thing in my books. In either case you have to deconstruct those shines when dancing. Your shines can express music and accent say second and sixth counts. Would you call that on2. What if I am expressing clave hits with my shines (many dancers do that), how can you justify that as shining on2 (or on1)? - you could do that with feet movement, with chest pops, with shimmies, with rolls, etc, and any combination, including your feet not moving at all or planted in place. Or I could accent the downbeats if there is an instrument loudly playing those. Depending on the phrase of the music too, you can decide how you want to express it.
How do you dance shines on2 only? Care to explain?