Great post. Selfies are definitely a type of portrait. Whether they are good or not depends on the individual case. The quality tends to be lower than other portrait photographs due to the use of phone cameras and the inherent difficulty in photographing yourself from a practical perspective.

There is nothing to stop someone from creating a high quality selfie using a DSLR, tripod and timer (as you mention) bar the inconvenience of doing it.

I agree that there is some degree of vanity involved depending on the person. The kind of people who constantly take selfies seem to be trying to prove something to others about their lives and get attention.