I never had an issue finding groups. I've done +4 with 2 companions and it worked out fine.
Yeah doing +4s with two people with a companion each works out just fine.
I think part of the issue is that there no way to summon party members. Some of the planets are just so large that people don't want to join groups for quests if it will take them 15 minutes to get there and 15 minutes to get back to where they were.