Unfortunately, bwmon and quotas are actually some of the harder things to pull out! Trust me, i looked lol.
Plus, i think that bwmon and quotas are very useful components of the firmware. I know that people trying to push faster internet speeds aren't the biggest fan of bwmon, but, if you're trying to do 300 down the autobahn in a Daihatsu Charade that's not my problem

So we have some firmware profiles where USB is not included, but i think it is important that where a device has a USB port that we include support for it. Particularly, this allows us to go down to a minimal firmware where you can then use that USB environment to extend the filesystem onto it and regain a full version of Gargoyle. We'll see how that works. In my testing, not too bad!
VPN is definitely out, but again once you've got a usb stick in there you can add it back no problems.
Tor is the same story, though i agree with your assessment.
The time server is more about keeping the router in check and the bandwidth history accurate rather than the clients. Not sure i agree with this one but i know some people prefer a local time server.
Geolocation was a necessary step for me to provide any regulatory features at all (at least, any exposed to the user) as it was not approved without them. I tried this before and the idea was rejected. That module is only 4KB so no big savings to be had by cutting it out.
IPv6 is actually now very hard (read: i don't think possible) to remove. A lot of the dual stack code in the kernel is now fully integrated and there aren't heaps of savings to be had by cutting out what you can. The web of complex dependencies also means that we have to include bits and pieces of it these days. Plus, in the future i'd like to make Gargoyle fully IPv6 compliant so it's nice to keep for now.
The regulatory stuff is basically all controlled upstream and i have no intention of touching it. If you are experiencing the problem only in Gargoyle (i.e. Openwrt behaves fine) i'm happy to look at the individual case though. Your regulatory settings may need some tweaking (within the extent of the law, that is).
DDNS has been pulled out and turned into a plugin.
QoS has been pulled out and turned into a plugin (and boy was that a mission). That module takes up almost 250KB on its own.
If you've got great ideas and the knack for this kind of thing, please feel free to jump in and give a hand too! I'm always happy to take assistance.