The issues at stake were huge: knowledge, progress, and thinking vs. a fundamentalist viewpoint that religion was the only guide to moral and ethical behavior. Typically, it is referred to as an evolution-creationism debate; or as it's called these days: an evolution-intelligent design debate. It attracted widespread attention because it was controversial. It was illegal (at least in Tennessee where the trial was held) to teach anything that disagreed with the story of Creation in Genesis in the Bible. Both sides saw this as an opportunity to make their case in a national arena (albeit in a small town). So, each hired high profile lawyers (William Jennings Bryan on the religious conservative side and Clarence Darrow on the Darwin/evolution side). Such notoriety increased the already high profile case.
In the end, this trial was more than just a popularization of an ongoing debate. It was a rift between religious doctrine and scientific study, with scientific study being more open to new ideas, developments and 'evolutionary practices' whereas religious zealots stuck to the Bible and all its literal interpretations. It may have, however, led to some religious progress (some Christians accept evolution as a part of Intelligent Design). The trial also may have contributed to the growing political divide between conservatives and liberals: instead of having an open and honest discussion, evolution/creation has been appropriated as a way for each side to mindlessly oppose his/her political 'opposite.'