My 2 cents

I have no competitive (and barely any casual) brood war experience, so I'm going to talk in fairly general terms.

From what I know, brood war's mechanical limitations (12 selection cap, no worker mining rallies, no multi-building selection, etc) made the relevance of strategy very minimal because of the sheer power of mechanics. Having better mechanics than your opponent in starcraft 2 makes victory quite likely, but in brood war even at the professional level it made victory certain. It also makes for an incredibly high barrier to entry, because it feels more like you're fighting the game than playing the game. 

Any discussion of the skill ceiling being higher in BW in my opinion is completely irrelevant. In a competitive multiplayer game you're competing against the opponent, which means that unless both players are playing 100% perfectly (which obviously isn't the case) the skill ceiling is a non-issue. However, for the reasons mentioned in the previous paragraph, the BW skill ceiling is significantly higher.

I am told that positioning and unit control were more impactful in BW than in sc2 (where unit composition and concaves are the key to winning fights). If this is true, then I would say that it is a point in BW's favor. In my opinion things that fall along a gradient (positioning) are inherently better than boolean options (do I have colossus tech yet?). Obviously the quantity of tech units is somewhat gradient, and in tvt for example getting a good balance between tanks/vikings/medivacs/bio is probably quite difficult and impressive (I don't play terran, so I can't say for sure). And in tvz pretty much the same composition is used every game so it comes down largely to positioning and micro. zvz and pvp I think are probably the worst offenders, as it's basically "well, he teched to hydras while I wasn't looking, and now I need to get banelings to be able to take a fight" or "whoops, colossi just destroyed my entire army because I only have gateway stuff". Positioning in zvz roach vs roach battles is important, but only as far as initial concaves goes, there's little room for micro in the fights themselves. pvp early game fights are quite good imo, with both positioning and micro, but late game fights are entirely decided by initial positioning and unit composition (and possibly reinforcement distance from warp ins).

I think a lot of micro in BW consisted of working around the unit ai. Microing dragoons is a lot more like babysitting them than microing them. Fighting with pathing to get lings to surround a target, etc. Unit movements were jerky and occasionally unpredictable. Starcraft makes control much more precise and deliberate, which in my opinion is a good thing. It makes micro easier and less impactful, and it can be debated as to whether the trade-off is worth it. There are some obviously some examples of course that go against these points; mutalisk micro in BW I hear was quite good.

As far as positioning and deathballing is concerned, sc2 definitely encourages allows deathballing more. While BW had some design differences that may have allowed for less deathballing, such as overkill on siege tanks, the simple fact is that a larger army beats a smaller army with fewer casualties (see lanchester's laws). This means that in most cases, there is no reason to take an engagement against a larger army, so splitting up is only necessary to actually be in more places at once. It could be argued that more bases were used in BW and so more area had to be covered. I'm not an expert in BW so I can't comment directly on this, but I will note that sometimes sc2 games go up to as many as 8 bases on either side, and that's the stage of the game where I think deathballing occurs the most (since neither player has a supply advantage at this point, so it's impossible to split without being left with a smaller army). Instead, a primary army deathballs around while small harassment squads go off to do stuff. In BW deathballing I believe still happened, but was less common due to the 12 selection cap, because deathballing was simply more difficult. Splitting up was also more difficult, so it doesn't only go one way, but I'm not even sure if deathballing actually was less of an issue in BW and am simply going off what I've read (which is probably largely influenced by nostalgia and romantization on the part of the people writing what I read).

 

Overall, I think that sc2 is better than brood war. I think that any potential loss in positional play is more than made up for by the more intuitive and cooperative mechanics. Simplified mechanics allows for more room for strategy to decide the winner. I can make no statement on balance in brood war, but it's really damn good right now in sc2 so I doubt it was much better in BW.