The game is designed to give priority to the player who wants to listen to dialogues and watch cut-scenes, within reason since there is still a timer involved possible choice.
That's how the game is supposed to work either in Story or Hard Mode and you can obviously expect in PUG to meet someone not "spacebarring" for his own reasons: it could be his first time, or it could be he simply enjoy it every time, or simply he does not like rushing through the dialogues.
Enjoying the game is not only about rushing fights and grinding gears. Every player enjoys SWTOR for his own reasons.
Same goes for people complaining that a tank is doing all the bonuses, or not skipping lower level enemies and complaining he should just rush toward the bosses for loot.
When teaming with random players, if one wishes to play a "spacebar", "boss rush", "barehand only", "kinky naked run" or whatever specific style, then one should expressly state so. So others can choose accordingly to group with him or not.
The problem is not about "spacebarring" or not, it's just about the lack of communication.
Some people don't want to take the time to talk a minimum when randomly grouping ( I really just mean few words to clear things up before starting), then they should not be surprised to encounter misunderstandings once into the action.
On a related sidenote, the current Group Finder implementation is not enough on a social aspect, as it does not allow more filtering or input information other than TANK, DPS or HEAL
Are kinky naked runs going on? Because.... I would so join that.