First of all, it still in Beta. So there will probably be a few changes and tweaks until the real first release.
About posts burried after 30 min, it is just a matter of reorganizing the Feed algorithm : for now it justs takes latests posts.
But with a smarter algorithm, you could easily have, as in FB, a Feed that presents you first the authors that you upvoted/commented the most for example. With a judicious random function to add Feed content that you "could" like (by analyzing which tags you upvoted the most etc..). It could quickly become much better.
Anyway, you can still add a link to your older posts at the end of your new posts.