As we all know every body is different and every body have different taste, so I was thinking it would be a great idea to give the freedom to chose their theme from the list of the installed them of OSSN, and can do this from ones setting page.
Now I got your point.
Have in mind that themes are/were made by different contributors who might not feel obliged to update their work whenever other themes got updated.
The theme will become active only after login and for non-login user the site can render the theme that is been set from admin section.
I thinks each themes use to pull the data from the database and themes use to place it accordingly in correct location in order to get a complete website, so I personally don't fell there is any great issue, as almost every themes are responsive and they feats well on any screen.
because different themes may have different dimensions and different functionality.
Due to the many requests in the past for additonal features and components we have decided to develope a premium version. Features like Hashtags, Videos, Polls, Events, Stories, Link Preview, etc included in it.
$199 (Life Time)