To me, while it may be a cost cutting exercise, its costing GW big in another way. PR. As you can see, some of our most talent and experianced members are gettting annoyed about this (quite rightly in my eyes). And Heresy won't be alone in this. The problem is is that moves like this reduces choice from the gamer as they are forced to buy bits they don't want. This obvisouly annoys people as they are having to pay money for stuff which they are just going to have lying around or waste. Yes their may be some bags that are full of good parts but there will also be bags with stuff that is mixed and some with only one good thing. Also there are going to be parts that people may want that arn't going to be in the bags. And what about older parts from the archive range? BWB doesn't sell them as far as I know. They arn't going to be in the bags so where do you get them from now?
Now yes parts you buy but don't want can be traded for bits you do but I can tell you now that even with this there are going to be bits that nobody wants which they ahve payed money for which before they wouldn't have had and wouldn't have payed for.
It also could create a monopoly for BWB, as soon as you start removing consumer choice of where to go to get their products the places that are still in business can do what they like with the prices.
Now considering the amount of GW Bashing that goes on (Rightly or wrongly, im not taking sides) PR is something that GW desperatly needs - especially from gamers in the older age bracket. These older gamers generally arn't happy with the way that WD has changed and the jury is still out on whether the rules streamlining is a good thing. Combine this with the price hikes (again not taking sides - but you can't deny that the price of the hobby has risen a fair bit in the past 5 years) and the atmosphere isn't all rosey for GW.
As for the idea that this is a cost saving exercise. I don't beleive that is true, I think that the way they operated the bits service before would have been working fine however they have come up with a way to make more of a profit. The idea that the cost of employing warhouse staff and packaging is too much is laughable. The chances are these workers arn't employed soley for individual parts orders, they will be packaging together normal kits as well.
My take on it is that this is designed to move more stock. GW is a business and its aim is to make money. Now unfortuntly this sometimes comes at the cost of annoying certain demographics. It may do make more money for them, it may not but the chances are the one thing we can count on is that PR will take another hit. It all depends on how many more hits PR can take before a policy reversal.