Yes, and it is no surprise as the web becomes more accessible and as such a place for entry-level designers and developers.
The biggest culprit at the moment is the overuse of Twitter Bootstrap for all the wrong reasons. It is supposed to be a framework on which you build your own designs and write your own code, but it is becoming a theme template for those that aren't able to design or code.
WordPress is another of those scripts that has become a favourite of both entry-level developers and people that cannot code, which is why you see it everywhere, but very rarely on larger, established sites. Again, probably a reason why many of these blogs look the same.
If I were you I'd steer clear of WordPress if you have an interest in building sites. WordPress might have been the best option five years ago but it's now 2012 and WordPress is a poor solution to build a site from. It has a terrible code-base and quite frankly its not even a CMS.
If you want to get involved in front-end code I'd definitely have a look at Twitter Bootstrap, but remember to modify all the elements so that you're not just ripping the design.
If you want to get involved in back-end code then I would look into either [Concrete5 if you want to use PHP or [url=http://www.umbraco.org]Umbraco](http://www.concrete5.com) if you don't mind using ASP.NET. Both are great CMS's and although I prefer Umbraco both are great for new users.