The page name field in Adobe Analytics is a free-form field. That means it can accept any string that you pass to it. I believe this was decided waaaaaay back in the early Omniture days to give clients the flexibility of what they defined as a "page name". It will only use the page URL if you omit the "pageName" field in your Pageview s.t() beacon. (On the other hand, Google Analytics has standardised on the page URL as the preferred page name.)
The recommendation from Adobe has always been to define your own standard. Of course, the easiest is to parse the URL since the URL is supposed to be permanent. Some organisations have chosen to always define their own page names regardless of the URL or page title or other parts of the page. And then there are some, like you, who use the page title, assuming that it is permanent too.
Whatever method you use, I think the main consideration is "permanence". This will ensure that you're able to compare historical page reports reliably without needing manual manipulation, e.g. if a page name has been changed over time.