In reply to Seth.

Hey Seth—
The size issue is somewhat unfair. WordPress, uncompressed, runs at about 16.9 MB. Jetpack, uncompressed, runs at 6 MB—if you exclude the language files included in Jetpack.

WP doesn't ship with any language files and, for the moment, there isn't a way to have a translated plugin without shipping all languages to everyone (unless you ask the user to manually download and upload a file). Those files aren't called upon unless the WPLANG is defined in wp-config.php to a non-English language.

That's changing in the near-ish future once language packs—the ability to on-demand ship translations to only the users who need them—are rolled out to plugins.

With the module approach, the modules that aren't activated aren't called upon, so those files are just sitting on the file system. They wouldn't be in active memory and wouldn't impact performance.

Cheers!