One option for theme developers on the light weight side would be to add a half dozen options (Not as a contradiction) of the most popular ,useful,easy to configure, plugins as a 2 click link for any of these plugins.In other words,installed but not activated and with brief but concise descriptions of each optional plugin. Personally I like to try and use themes that have one click color theme options with one,two or three column layouts also as one click options; or single column with one or several sidebars.Since options involve php and javascript files,any theme can be introduced as a lightweight basic theme and a developer can offer any or several options as "optional" updates configured like a plugin, in the admin interface.This thus can allow for uninstallation of options.