I don’t think it makes sense to conclude that they are playing in a way that invalidates the changes they made.
Did they change the ranges and ground scale to slow movement down, as you suggest? I don’t think so, or rather, that was not the goal in itself. The initial turns of most, perhaps all, miniatures games are about moving into position. And obviously this is especially important to Alpha Strike because of TMM. They clearly don’t want to avoid those things, as you noted.
So why the changes? I think they explain it themselves and, as I recall, it has to do with using a 4x4 play area without invalidating mechs that want to work at long and extreme range.
As to the damage rolls, let’s explain it for the folks at home:
In Alpha Strike, each mech makes a single attack — a single roll for all or nothing damage. A lot of people, myself included, find this extremely boring.
One alternative is to roll 2d6 for each point of damage a mech can potentially inflict with an attack, which means rolling 2d6 a number of times, separately, in a row. Statistically,
this method does not produce significantly different results than the basic rule over a large number of rolls. It’s just more fun (YMMV) than the all-or-nothing baseline mechanic.
But even so some people, myself included, find rolling 2d6 for each point of damage tedious. So the further modification is to roll a single d6 of one color and as many d6s of another color as the damage value of the attack such that each point of damage rolled shares one of the d6s making up the 2d6 roll. This is generally referred to as the “pilot die” method (as the shared d6 is said to represent the pilot’s contribution).
I’m not sure what you mean by “skew” but the pilot die method wouldn’t produce statistically different results from the baseline or multi-2d6 methods. Conceptually, it’s a compromise between the two. While not all-or-nothing, if the “pilot die” rolls low, you’re more likely to do less damage but there’s still the chance of doing some.