Getting back to the critical question of a good scientific explanation: necessary and sufficient -- the big question is whether the notion of Intelligent Design in any cosmic sense is necessary to account for observed phenomena. I thin the general thrust of ID is to call for it as a competing theory to Darwinian natural selection.
The argument against that is that it is wholly unnecessary if you take into account the constraints of evolution.
First, it is not random change that brings about evolution. The same sort of "ordering" from basic physical process, for example, that sometimes makes big rocks on a beach all gather in one band and tiny ones in another -- a non-random result -- is present in thousands of ways in life's interactions.
Secondly this sort of crude sieving of factors is not simplistic, in that an ordinary organism in its search to survive is involved in thousands of such forces every day.
Thirdly, the results of these many influences of ordering are not single-step. They are cumulative. The difference inherent in this one point is one of orders of magnitude--if changes are preserved on some sort of merit, or some sort of ideal to be approached (this is where ID gets its kicks just like the old Social Darwinists did) then the rate of change in that direction is millions of time more advanced than if every change is a single step with no additional force selecting some as preferable to others and passing those selections down the line to the next iteration. Evolutionary modifications are TINY but they are CUMULATIVE.
Finally there is no need, given these factors, for any more "guidance". "ideal", "goal", or "design" than just that reproductive success and success in surviving be slightly better. That's all that is needed to account for the complexity, harmony and adaptation of all our millions of life forms. There is no reason either to assume that evolution is progressive, culminating in proud fat white people, NOR that it is prescriptive (steered to a longer term goal by external direction).
I think this is the basic perspective a biologist would present, and it seems to me that it does indeed obviate the need for intercession or design of any kind, other than the intelligence of the individual organism in seeking to survive better. Maybe even not that.
Arguably more intelligence would accelerate the emergence of more survival behaviors, but they in turn might well be dependent on the number of perceptics a given organism can manage biologically.
This leaves out spiritual questions almost completely. Possibly not a good idea in the long run, but acceptable for a discussion about science 21st century style.