Indeed, the high speed made it worse, MCAS ran 50% faster main electric trim.
In addition to that, MCAS didn't stop at around 4.0 units of trim with the flaps up, like the main electric trim does, and also MCAS couldn't be stopped by pulling on the yoke.
The intermittent nature and the 4x feel force are factors that probably confused the pilots, not to mention the additional physical effort required to fight that.
Counting, there are 5 reasons why a MCAS induced stabilizer runaway is worse than a classical runaway. Or 6 reasons, if we include the fact that the Lion Air pilots didn't even know MCAS existed.