I think a lot of it has to do with the lack of titles. Or in the case of the US title, lack of focus. Back in the days, it was a big deal to be a contender for ANY title, be it the intercontinental title, cruiserweight title, european title etc. They put a lot of focus and importance on getting those title shots. That is SUPPOSED to be the purpose for being there. Everyone wants to be a champion. But with the way they have been carrying on these last few years, swapping titles like trading cards, it has belittled the credibility of the titles.
Being a champion and holding a belt is supposed to distinguish who is the best at what they do. I remember the days when The Rock and Austin were way over, but they still treated their feud for number one contender for the IC title as the end all of their careers. The way they put over the importance of just being a contender gave merit to what the title was SUPPOSED to be. There is no motivation for anybody to do that if the angles favor more towards 'flavor of the week' champions then it does to actually award someone for anything.
As far as the tag team titles, I frankly don't know why they even have them anymore as there has not been a really good tag team division in a LONG time. Who is a tag team? Legacy is the only credible team even worthy of holding titles. And even if they DID have them there is nobody else who can legitimately compete for them. DX? Come on.
They have the talent but don't know what to do with it. It has been a long time that the mid card has had any real organization. It's like the writers cannot find a way to balance the two different levels. So instead of finding a way to harmonize they just let these guys flounder around with no real purpose. Instead of creating a storyline that will allow these wrestlers to grow as entertainers, they yoyo them back and forth, pushing them one week and jobbing them out to someone else the next. I fail to see the purpose of having someone like Evan Bourne demolished by Sheamus.
Guys like Cena, Sheamus, HBK, Orton, HHH, all of them are already established as the cream of the crop. There is no need to prove that to anyone by burying someone in the mid card. The two need to be kept seperate.