The lack of page/section styles was one of the first features I noticed missing in Pages 5.0. This is really disappointing for me as I've created a number of my own document templates and have made extensive use of page/section styles.
On one hand I can understand why Apple may have removed this feature. It is rather an anomaly among its peers. Microsoft Word does not use page/section styles and to some users it could be a bit of a confusing feature in Pages. I know for me it was somewhat confusing at first. I was used to the MS Word way of doing things and I was wondering how these section style templates differed from me just setting my own section style. But then I figured out that it is like a slide template in Keynote. It is simply a template and can be used as a shortcut to setup a new document section in a standard style. Since figuring out how to use the page/section styles, it has been awesome and has been one of the key reasons I like Pages better than Word and why I switched completely from Word to Pages.
For now, I guess I will have to figure out how to work without it which will basically mean that I will have to go back to the old manual method of just copying and pasting section styles. It will take longer to add new sections with identical styles to a document and will be more buggy. It is likely that I will not always get it exactly correctly which will result in consistency issues in my documents. As well, the inability to copy and paste whole pages/sections from the page thumbnails will make this process take even longer and be even more buggy. But ultimately it is doable.
I can only hope that the page/section templates is a feature that Apple will bring back very soon. I wish someone from Apple would at least let us know if this feature will be making its way back in or if it is gone for good. Accordingly, we could move on or plan for its return.