SharePoint site is not developer site - SharePoint 2013 deployment error

This is the first error I got when tried to deploy my first app to SharePoint 2013 environment. Full details:

"Installation of app to SharePoint failed: SharePoint site is not a developer site."

This not giving any full details about why it is failing. Below are the things I verified to resolve the error.

1. Please make sure the site is available from your developer environment [Where visual studio 2012 is installed]
2. I have created my default site [when I created my SharePoint 2012 preview environment] as http://sp15 with publishing template. When tried to deploy this site it was failing. So, I thought of creating another site collection with different settings. When I go to Central Administration, create a new site collection, under Collaboration tab of create site page I found a new option named "Developer Site" template. So, I have created the site collection in the same web application with this template with the url http://sp15/sites/dev. This time I have tried to deploy the app to new SharePoint site and it was successful. 

I am not understanding why the issue is resolved as the developer site template did the trick? More information I will post in the same post soon. Do let me know if you have any more details.