I'm just a user, not a developer, but I think I can speak to your suggestions:
1. That won't work because people and their systems are too variable. Not everyone needs a UTF-8 locale. For those who do, some will want ca_ES.UTF-8, others will want en_US.UTF-8, others will want something else. The boot code (which is what you see in /proc/cmdline) has to match the desired locale. Also, not everybody has extlinux.conf (for instance, I use grub2 and don't have that file).
2. As above. Different strokes for different folks. I prefer geany as my GUI text editor, not gedit. For folks who don't need UTF8 support, the more minimalistic aterm may be preferable over urxvt.
TCL caters to all by "baking in" only the absolute bare minimum. Each user can then add to that minimum base whatever he needs or wants. The end result is a bloat-free system that has only a tiny base and the things you've added. There are no unused things sitting around to clutter your machine or for you to figure out what can be safely removed.
I hope you can now enjoy your TCL system as much as I enjoy mine. I'm glad I could help you
P.S. Now that your locale is properly configured, you can use whatever text editor you want--you are no longer tied down to gedit. Most text editors have built-in support for UTF-8.