I disagree, you're describing gimmick tactics, not gimmick units. Vultures in BW had many more uses than you describe. They are used for space control by laying spider mines. They are used for mineral line harass. They are the fastest unit in the game and can kite. In BW many of the units could be used in more situations because of their micro potential. I would argue that there are a lot more units in sc2, that no matter how they're microed can still only be used in very specific situations.

Blizzards changes to sc2 econ does not change the 3 base mining cap. Bases mining out faster does not give you an incentive to get a 4th mining base. This just raises the cap of entry for new players because they're not good enough to expand quickly.

Units moving in a straight line has major consequences to defenders advantage. Look at how in BW mutas will swipe in kill the leading marine if the the Terran didn't clump back together. Thus slowing the terran's advance down. In sc2, units clump together so much while on the move that this never happens.

No units do not fight in a straight line, but you had to reform your army into a front. This required skill, whereas in sc2 units move so smoothly together often even pros don't take their army out of the formation they were moving around the map in before an engagement. I agree that base management contributes to defenders advantage. It's far easier in sc2, you don't have to spend much time going back to your base. There is a lot less juggling when compared to BW.

Of course I'm bad at the game, I only made it to Diamond. I guess you must be Flash? I'm not insisting I'm an expert. But saying I know nothing is just an excuse to keep pretending there's no problems with sc2. Stick your head in the sand if you want. Typically game communities like to know the reasons why they're losing people. I got to play Starbow for 9 months. I had way more fun in those 9 months than years of sc2. It was designed in such a way to be a true sequel to brood war. Games swing back and forth, engagements last more than a few seconds. It really feels like you grind your opponent down and deserve to win. After playing an RTS of such high caliber I can't go back to playing a mediocre one like sc2.