Moe (萌え?, pronounced [moe]) is a Japanese slang word. Moe is not a concrete term. It is constantly evolving and being used in many different ways. Moe is a feeling or characteristic. Despite the belief of some, moe is not a genre. The term "moe" can be tacked on to the end of any personality trait or physical trait to create a new type of moe.
Just want to preface this with, I'm totally fine with people fan(boy/girl)ing over anime they truly enjoy, this is more about the lackluster anime that have spawned after the K-on craze.
The term "moe" has been around before K-on, but I defiantly think K-on itself has brought it into light and made this overabundance of anime focused on moe rather than compelling stories and believable characters. What's even worst is the fact that they follow a "K-on formula" that consists of a primarily all girl high school with a four female cast in the flavor of a slice of life.
I've enjoyed the first season of K-on just as a non-serious anime I watch, but I can say the second season ruined it for me and as a result I end up avoiding any anime with four female characters as protagonists.
The rampage of moe also kills off the space for original characters in place of stereotypical trait like tsundere and in some casts yandere. Tsundere seem to pop up more often than its counterpart a lot more in anime and I've never actually liked tsundere in the first place.
Essentially the main complaint I have toward moe is it's dumbing down of characters and story doesn't help the overall image of anime as a medium of telling a story or entertainment. I guess that is the symptoms of something becoming popular, everything is simplified to appeal to the masses.
Whatever happens to the future of anime well can only hope for something brighter. I'm pretty happy with some of the anime that is coming out, but there really isn't much to pick from that appeals to me.
To wrap up, as a little bit of irony, I was the one that made the demotivation of "Moe Moe Kyun Beam" way back in 2009, but all credit goes to the artist nekomamire that actually made the picture itself. One thing I'll credit "moeification" of things is the artwork and in cases the sub-culture built around it, but it still need to calm down for the time being.