I also don't like playing with heroes all the time, but without alliance/guild that is the best there is.
For me, there are two main reasons to Hero/Hench missions.
First of all: time. Putting a full human team can take time. Heroes/hench can be set up in one minute.
Second: Player skill. I've seen some bad PUGs yesterday in Hell's while helping a friend. That mission is easy with heroes/hench!
The second attempt I put up my monk heroes and my SS hero and they still managed to fail because one player (yes, W/Mo) was playing very bad.
This on a character I have very much experience with and that has done Hell's numerous times because of skill caps, exploration and helping others.
Solving those problems:
Time: make something like a 'sign up' for a mission, where people get a notification when enough players have signed up. Accepting the notification brings them to the mission outpost.
Skill: you never know who you meet, but some encounters can be quite nice.
I had PUGed with several of my current guild members before I joined.
I've also got a number of people on my friends list that I teamed up with a few times in PUGs.
And sometimes when you wonder why things are going smooth for a PUG, the emotes start to appear and you know....
I still enjoy PUGs now and then, but the guild keeps me quite busy at the moment.