But the sixth installment clearly wants to distance itself from all the others.

In general, this is a rather sensible approach. It's not always possible to maintain the series' traditions (the Warlords changed genres twice), and as a result, fans are dissatisfied. Here, the developers immediately stated that these are new heroes, so that fans don't come up with all sorts of things. Yes, the changes themselves are debatable (especially the reduction of resources, although everyone got used to the absence of oil in the third installment, I think they will get used to it here too), but that's a different question.