I'll echo the sentiments of many before me in this thread. If you're truly playing this game purely for the story in a single player experience (similar to KotOR 1 and 2), you're completely missing out by skipping the side quests, especially the main story arc for each planet, while you're leveling up. And I'd even argue the level appropriate flashpoints as well. All add to the over-arcing story of the game and are what make the game great.
Also, I'd wager that 75% of the "kill 10 rats" type quests that you despise are bonus quests that are completely avoidable and don't add any extra story.
Honestly, the most time consuming part of working through the content in this game isn't killing trash mobs, it's travelling across big planets. The side quests and class quests progress to the same parts of the maps at the same time which is actually a time saver in the long run to run them concurrently and the rewards for these quests will easily keep you geared up for the content you on each planet.
Based on what it looks like you want out of this game, you'd be better off doing the side quests along with the class quests but just ignoring the bonus objectives that pop up. Then you wouldn't have to worry about how to gear up, worry about kill counts, or miss any story.
The 12x class quest xp bonus was really a perk for players that had leveled numerous alts but burned out on leveling more because they had seen all of the side quests 5+ times. This allows them to see the NEW content (i.e. class quests they haven't played yet) without having to replay the side quests for the seemingly hundredth time. I play this game primarily for the storylines and I wouldn't dream of skipping the side quests on my 1st playthrough on each side. That'd be like playing KotOR and never engaging a single NPC in dialog that wasn't the main story NPC. You'd miss 80% of those games too.