That's Dangerous, onii-chan!

The potential for vanity in everyone had always existed and probably have never changed.

There is a misunderstanding, I'm not driving at people being vain. For instance, I don't think picture threads are popular due to people having a high opinion of their own appearance. I think their popularity has more to do with the high level of general interest in what other forums users look like. There is an intrinsic interest in the physical appearance of other people because attractive people stimulate seeking behavior and are a positive reinforcement in changing behavior resulting in people gravitating towards such threads out of biological impulse. It's just humorous that forums which trend to be coded for content sharing with anonymity have personal picture sharing as a hot or popular community topic.

The values that new blood grew up with are different than veteran users and have different priorities and focus.

Disagree. Core 'values' remain the same throughout generations. Financial independence is hardwired into our animal instincts of self-survival. Ancillary beliefs are just sub-values to making sufficient income to afford a house, food, and basic provisions. For instance, the recent surge in students receiving an education is just being massively perceived as a means to an end for students to get a decent job to afford all their basics when they graduate.

For them, the newer social media is simply the best tool to indulge their unique perspective while the older generation had their own ways.

Using a rendered image from a popular source of media isn't contributing or conveying whatever 'unique' perspective the person has to the rest of the audience. Rather they are diluting their own opinions by using another medium of expression. The reason why rendered images are popular is because they are identifiable and easily understood. When people use them they are trading in their own form of expression for a similar expression created by an image, macro, or gif. And yes, the 'older generation' which I assume you mean everyone not using new social media to divulge personal perspective used words in order to express personal thought. We actually assembled the words in our thought factories before shipping them out to public consumption. We sure had our own ways.

Also, pictures are popular because they are a quick and easily consumable medium to spread an idea, and it's not really anything new or bad. If anything, to be able to convey an idea with just a picture can provoke more thought and interpretation and may in turn create more discussion.

Quick and easily consumable medium has a habit of toning down the original message to appeal to a wider audience. What happens is that a wider audience understands the medium because it's been sanitized and having quickly consumed it they leave quickly looking for the next image so they can get an emotional high. I don't understand how something that's easily consumable would leave itself open to interpretation. Nor why you think it would be more open to thought than say something that is harder to understand. I don't see a lot of people asking for advice in Rubik's Cube about basic concepts in psychology or sociology simply because those classes are a joke and the information is easily understood. However, I do see a lot of programming questions and people looking for discussion on how to solve a difficult problem that they can't figure out at the moment on their own.