First of all - you're not forced to do those quests. You're free to skip every single one of them that you want to.
Unfortunately, this is not an viable solution.
Players want to enjoy the content NOW, and get the Modable items which they can keep throughout their leveling adventures NOW, not have to come back 5+ levels later and solo the entire dungeon.
Second of all - if you're spending all your time "LFG", then you're doing it wrong. Keep questing until you find people, then gather and knock it out.
This is also not useful, since many players will elect to ignore other players, other than buffing them for courtesy sake and helping them out in a pinch (if the player is about to die) if they are able to. I do both the former and the latter all the time, but I rarely ever invite other players for Heroic 2 or 2+ zones, since thats what my companion is for.
If I am unable to complete said quest via attrition, then I simply move onto the next quest and do it later, 1 or 2 levels adjusted.
This is not an issue for quests, but becomes an issue for flashpoints, since the whole point behind a flashPoint is to have a group to do it with.
While Im perfectly fine with solo'ing or dual-boxing everything (where mathematically possible) by myself, (the end-game is my goal, not the leveling) most people play this game for the social aspects.
The goal is to make grouping "optional", not required, with the exception of course being the the end-game Raid encounters.