On the question of how these closures will effect those 'down the line' I'd like to add my tup'ence worth.
As someone who works in an M&S DC that supports two of the stores that are being closed I think its worth bearing in mind that when the stores were (pretty recently) opened we didn't take on any extra staff to deal with the extra workload. The larger stores are the ones that require the greatest amount of labour to support with the smaller stores being slotted in around them on the loading and dispatch schedules. As a result no-one (other than the usual paranoid, anti-management few) is worried about the job losses.
The logistics side of the business (DC's, suppliers, transportation) has always been the part that the M&S hierarchy targets first for cut-backs when times are tough. As a result they are the areas that now have the least amount of slack for trimming, hence the decision on store closures and job loses at head office instead this time, which obviously grabs the attention of the press a little more.
The Simply Food stores were an obvious target for closures really. The food they sell, although good quality and ethically sourced is unquestionably more expensive than that sold by some other companies and when money is short most people will dump ethics and taste for cheapness, hence the popularity of stores such as Lidl and Aldi.