To answer this question:
Lets lay down some basic methodolgy and points about registration and how social media integrates with these systems.
- People dont like to register for things, especially not with their email due to spam and unsollicited messages concerns. Its often a hastle
Make registration less painful by letting users register using their preexisting facebook and or google accounts. read here for more advantages
- Succesful social media heavily relies on customer/user retention. But not neseccarily on user real life authenticity. You can have a great user pressence that isnt tied to personal information or reidentification.
The lesson learned: Not all social media requires accounts, full anonimty is an option
Now if you insist on a user registration base, you must make registration:
- not a chore
- geninueinly useful
- feeling required, by both you and the user
Ebay for example realizes this, and lets you check out and use ebay as a guest because it knows that for some people registration would be a hastle and not useful. yet it clearly displays the advantages to registration on ebay
On your UX concern:
You should follow suit, make registration useful and people will register. When they are logged in as guests make sure they know what the advantages of registration are and prompt them to do so if the action they want to perform requires an account
As a side note:
I can tell that a button or an option that lets you continue as a guest will be often used and that it bothers you, and sadly if your app is not very promising or engaging it will be the majority of users.
Its up to you to make people not only register but also use their registered accounts. unless you prefer a massive amount of one time use accounts with pracitcally zero retention