Well, as much as I hate to use Illustrator as an example, everything in Illustrator is a plugin. All of the core tools, all of the effects, the dialogs, etc.
If there is no difference in terms of performance, would this still be bad in your eyes? If it's 100% transparent to the user, and if it could somehow cut down compile times, it makes sense for all of our existing tools to be refactored into plugins as well. Note, none of the above may actually be practical... but I figured I'd ask (and point out the AI thing).
-Josh
If I may give here my opinion as a user, it would be better for me to have all the tools implemented as plugins for at least for 1 reason: updating these tools would be a lot more easier (download 1 or a few plugin files and paste them in a "plugin" folder, instead of downloading and reinstalling Inkscape). Also, users could choose what tools they want or don't want during installation (in case in the future there will be specialized tools, for example a codebar generator or something like that...)
Molumen