People started playing around with Bitcoin because it was something new and exciting, it was truly the first of it's kind! Ideas were being thrown around, more and more people started joining the ecosystem, mining was getting really competitive, Bitcoins found their place on Silk Road, etc.
The point I'm trying to make is that Bitcoin was first! And all that excitement and experimentation over time translated into monetary investments and architecture, something the alt coins will have to work really hard to obtain! Not saying it's impossible, just highly unlikely.