Here's something I wrote recently in response to the abvoe question:
Traditionally festivals were a way for communities to come together and connect. The original idea behind a lot of festivals like Holi and Ganesh Chaturthi (started by Lokmanya Tilak for a socio-political reason) was to provide a platform to bring people together. Most festivals are not necessarily about religion, but they celebrate relationships for example, Raksha Bandhan, Karwa Chauth, Ras Leela, Tulsi ki shaadi, etc.
Most festivals are symoblic, for example Diwali for me is the victory of good over evil in a society. Similarly, both Chinese New Year and Christmas are no longer celebrated for religious reasons, but more so, as an excuse for families to get together. People come back to their families from any part of the world purely for a reunion.
Some festivals are definitely marketing gimmicks, for example, Santa Claus was created by Coca-Cola, Friendship Day and Valentine's Day, I'm sure is a Hallmark Card creation.
Personally for me, I enjoy these festivals, as long as they bring people together and strengthen relationships. I'm a little put off by the commercialisation aspects of these festivals, and the unncessary noise and smoke created while celebrating them.
Thus, I would ask which aspect of our festivals do we want to leave for our future generations?