I disagree the statement that teachers gained more appreciated and valued by society in the past than nowadays. This could be a misunderstanding with the development of civilization according to 2 aspects, study patterns and communication methods. The comparison of past  and present days on education in China will be used as an example to give a further explanation.
First, study patterns have changed a lot from old periods that Confusious taught his students all the knowledge by himself while nowadays all the students go to school and taught by different teachers on different subjects. As a result, students spend less time with each of their teachers but it does not represent these teachers are less valued. The real situation is that modern teachers know more on their subjects and also have deeper understanding of it. 
The other change on the communication methods may explained the misunderstanding as well. With the development of technology, it becomes more convenient for students and teachers to exchange their arguments and opinions. In ancient China, students can only use letters or go far away to ask their confuse during study. The time and money costs on the way seems show more respect to teachers. However, the fact is that both students in nowadays and past are appreciate to the efforts that teacher brings. 
In conclusion, with the development of civilization, people becomes more freely than before and teachers also be closer to people. The change in study patterns and communication methods may bring misunderstanding that teachers in past were more appreciated and valued by society.