You forgot one powerful arguement: Re-roll in a high-population server!
Yeah. I already made a thread about this, got pretty much the same responses. Let's sum up the arguments real quick.
1. Heroics are extra content. No one's making you do them. Well, SWTOR is a video game. No one's making me play it. But I do, because I want to.
2. Heroics are not meant to be done solo. No duh, Sherlock. The whole argument is that it can take a miracle of God and an act of Congress to get a group together to knock out a 15-20 minute quest that makes you choose between mod gear, a box, or commendations.
3. They're not hard if you have a tank and healer. Again, no duh. There is no content outside of a Flashpoint or Operation that can't be knocked out by a tank/healer duo. Try that with two DPS at the appropriate level, doesn't work so well. And this is coming from a guy that plays all three specs.
4. Use companions. I learned on my very first origin world that companions can and always should be considered base-line retarded, no matter how well you think you've configured them. Mako is good for eye-candy, Slicing, and helping out against the class-story elites. Not soloing a Heroic and keeping me alive when a combo Strong/Elites are kicking the tar out of me, even with her and mine CCs. And this is, again, coming from someone who rolled a tank.
5. Socialize and make friends. I don't know what kind of friends you have, but if I told mine to drop everything they were doing and fly halfway across the galaxy to help me knock out an optional Heroic, I wouldn't have friends for very long. Or a guild, for that matter. Hell, people lose their minds just when I spam General asking for one single random guy in the same area with the same quest.
No where in any of those is one thing properly explaining why 4-man Heroics are a needed and loved thing in this game. They're here, they're annoying as hell, they don't reward anything near making the effort worth it. They need to be either made easier to manage (bumped down to 2-mans, make less of them, etc), or need to be made worth the effort (better rewards, mandatory to complete planet side-quest saga, hide datacrons in them, etc.)