I agree with everything above, and especially this:
I want my children's experience of music to be both enjoyable and instructional, so as much as committing to taking lessons means committing to daily practice, it ought not to be at the expense of music as a delight and a vehicle for emotional/artistic expression.
I don't know anything about your child Quantum, but I think your children are going into high school this year? If they are really into music, one thing that happened for my ds (who is really into music) is that he has enjoyed the opportunities to perform offered both at his high school and in our community for kids once they reach high school age. He's still taking 30 minute piano lessons, but has expanded his music ability through other avenues. A lot of our children's friends also expand to learning additional instruments or giving vocal music a try etc when in high school.
One other note - I would want to be certain that expanding lesson time is truly meaningful in expanding what's learned vs just giving more to practice. Hope that makes sense!
Best wishes,
polarbear
ps - yet another note - if your kids are entering high school this fall for the first year (I'm not 100% sure that's where they are at)... I'd consider that if you move to a 60 minute lesson now, leave an open mind to moving back to a shorter lesson or shorter required practice time after school starts if your instructor is open to it. Both of my kids who are now in high school found they had many other new interests they were interested in pursuing once they actually attended high school, and they also found that homework time went up astronomically. This might not be the case at all in your area or with your students, but it would have been a difficult time for us to have made the decision to increase time spent on music lessons and practice for one specific instrument.