The other possibility is because a feature that is needed on the site is not enabled by default, and because it is a hidden feature you will not be able to activate it yourself.
If you search for this, you will find a lot of articles about how to solve it on a regular sharepoint farm using either command line or powershell. However, what happens if you don't have access to the server, such as in the case of SharePoint online (Office365) or a hosted environment?
In such a case, you need to use a sandboxed solution to enable the feature. To simplify this, I have created a sandbox solution that has a single feature called "Enable Managed Metadata":
To download this solution, visit my company's web site's code sample library or click this direct download link.
After you have downloaded the solution, you need to upload it to your site. Go to the site's settings page, and click the "Solutions" link to go to the solution gallery. Here, click on "Solutions" in the ribbon and then "upload solution" button. Browse to the file you downloaded, and upload the file. Once uploaded you will have the option to Activate the solution. This should also automatically activate the feature, so from that moment on you can start creating managed metadata columns!
While you'r there, would you mind clicking the "like" button for our web site?