I'd be genuinely interested to know how you define intensity? I don't disagree, I just am not sure what specifically you are comparing. Certainly there are computer games that require as much decision making, even micromanagement, as ASL.
The one thing I can think of that makes ASL unique is the wider range of possible outcomes - particularly extreme outcomes, which are in fact relatively common. In the basic sense you have units that are killed, broken, or unphased - but the actual range of outcomes includes far more, such as PIN results, critical hits, Hero Creation, surrenders, Berzerkers, leader creation, ELR replacement, sniper attacks as a byproduct, etc. When those extreme outcomes occur on 2's and 12's, and either a 2 or 12 will come up on average 1 time out of every 18 chances, and you have dozens of DR in a scenario - I'd say wild swings of fortune are pretty much baked in to the system. So the excitement of the game is also one of its most maddening characteristics - the joy of reducing an impregnable defensive location with a critical hit, or the agony of your perfectly sited HMG jamming. I wonder if those extreme results aren't a big part of the game's appeal. Not sure any other game has as wide an array of those results either.