Say I want to install Codeblocks(C/C++ IDE) using Ubuntu Software centre. But, if I do that I will install version 10, when I can have version 12 if I download package from Codeblocks website. The same happens with Eclipse. Ubuntu software centre has version 3.x and I can have 4.x from Eclipse website.
Question is why ubuntu software centre doesn't have the latest version of a software? Is this the lack of interest of developers, not to update their latest release on ubuntu software centre? or something else?
The default Repositories included with Ubuntu are maintained by Canonical and a few third-parties. They have to first evaluate all software and updates before they are allowed.
However that's why there are PPA Repositories that you can subscribe to. Most software developers maintain a PPA so users can get the latest updates as soon as they're available. You can usually find the PPA for a program by checking the Developer's webpage. Alternatively you can search http://Launchpad.net for a specific software.
Some developers don't provide a PPA however, and that's when you'll have to manually download the DEB install file each time there's an update and install from that.
Worst case, some devs only develop for Linux in general and you'll have to download a ZIP or TAR.GZ archive that contains install scripts or even just a self contained program for you to run.