SLOC counts for various version control systems

At work I'm currently using Git and Subversion and Mercurial for version control. Other people there are using Bazaar and CVS. Too many programs to learn! We need to eventually standardize on a primary third-generation distributed tool to replace Subversion, but it hasn't happened yet.

There are lots of opinions on which third-generation distributed version control system should replace Subversion. (I like Mercurial a lot, respect Git's power despite its ridiculous learning curve, and haven't used Bazaar enough to have a strong opinion about it, except that it used to be unusably slow.)

Here's one data point you won't see in all the comparisons: code size as measured by sloccount:

Name Version SLOC
CVS 1.12.12 136,873
Subversion 1.4.6 492,564
Mercurial 0.9.5 40,682
Git 1.5.4rc1 142,669
Bzr 1.1 125,637

Why is Subversion more than triple the size of any of its main competitors? C, two backends, language bindings, separate libraries for client and server, Apache / Webdav integration, separate admin tool, yadda yadda yadda. Do you really need all that?

Why is Mercurial less than a third the size of any of its main competitors? It's in Python, and there's definitely an aversion to feature creep, to the point where lots of features that would be core in other programs are extensions in Mercurial. (Note that the extensions that are bundled with the project are included in its SLOC number, while the ones you'd need to download separately are not.) What else? It is missing some features compared to, say, Git, but it's sure not missing two-thirds of them. Why is Bzr, which is also written in Python and has a roughly comparable feature set, three times as big?

How important is lean code? What features can the Mercurial team implement by the time Subversion merge tracking is done and stable? Is there actually anyone who can name all 143 programs that git put in my /usr/bin/ directory?