Well, let's not forget that only a small portion of the playerbase is at 50 in the first place.
I'm not forgetting that. But I see 50's all the time that just don't want to group. They got used to playing the game their way, grouping only once in a while when they felt like it, and they don't want to be forced. So a lot of them are going back to Alts, or just taking a break from the game entirely to see what gets done about it.
I myself have a really hard time finding TIME to do a Hard Mode flashpoint. I just don't have the 2 hours to dedicate to it right now. I can do 30-45 minutes, no problem. In fact myself and 3 other 50's helped out a level 43 with one of his heroics the other day just because HE couldn't find anyone to group up with.
Another problem is that between level 35-40, i've noticed a lot of players on the republic side have stopped leveling and are taking a break because, and I quote. "It feels like a grind now".
There are many factors to it, I know. Me personally, I'm hoping for Hard Mode Heroics at some point, that way I can pick and choose from all of the ones each planet has to offer and find one that fits with the time I have available.
In fact I would have no issues with the thought that I may never get to do hard mode FP's or Ops because of time constraints if I could group up or solo some of the smaller heroics when I wanted and not feel like I'm just steam-rolling the content.
Honestly some of the heroics were more fun than the Flashpoints anyway, in some cases. All the heroics lack is a boss that requires some weird game mechanic to kill. heh.