EC requires too much coordination for a random PUG. When it was play tested, players basically said that it just didn't work through a group finder. Also, the group finder doesn't rate your gear, so it is setup to cater to players in basic gear for their level. EC really can't be done by anything less than a group in at least 50/50 columi/rakata (unless you're really on top of things), and is especially true for a PUG.
I think this is not true. You can beat anything via GF, you just need proper setup I learned that lesson from doing LI hm via GF. It works like this:
1) get random Party
2) check gear of party members
3) vote to kick all that have insufficient gear
4) repeat 1) through 3) until you have proper party
Solving the coordination problem:
Nearly any serious player has either Vent, Mumble or TS, most have all 3. No big deal to invite all key roles (tanks, heals) and make sure the rest knows the strats via chat.
And an easy way to facilitate things even more would be to add a minimum gear requirement to all hms and ops in GF. So people can easily see if their gear is up to the job or not. It would be a really easy fix.