Children in Shul: Rabbi Yisroel Miller in his sefer “What’s Wrong With Being Human” discusses this in his essay on pardha Matos and the concept of gratitude (Pages 182 – 183). R’Miller mentions that in 1920 there was a book entitiled “Why I am a Jew” in which the auther wondered whether there would be Jewish people by 1970 being as Othodox Jews in America of that time where primarily aged immigrants. The elders of the community would see the youngsters drop out of Judaism and thus they felt that Yiddishkeit would die out.
R’Miller continues that B’H we now see all the Yeshivas and the children flourishing here and views this as pure simchah! R’Miller mentions that we should show our gratitude to HaShem for these children (even the noisy ones)
R’Miller concedes that we should strive to have proper decorum in the Shuls, however, he suggests that for this, we should start with the adults.