To get back to the OP and away from the name calling and look at some of the thing which have been said ....
It has to do with logistics. The minute a spring/guide rod comes off the assembly line, it does not drop directly into the customer service reps lap. There are packaging, distribution and shipping times to get it to the service department, and then the times to process your warranty claim and ship it to you. If the item is backordered, then those times are even longer. The fact that the rod was backordered and the rep was shipping you two guide rods tells me also there may be an issue with them. Maybe the delay is because of a fix or upgrade to the original part. I dunno. The M&P is a very popular firearm and a Google of it and it's problems shows no abundance of broken guide rods.
Add to this the fact that they are not going to take a part of the line because if they do there will be excess of the other parts which will not be assembled because of a missing guide rod. In today's world of just in time inventory you cannot disrupt the assembly line to meet part replacement issues. It would create a logistical nightmare.
S&W has excellent customer service. I would personally put them in the top 3 with Ruger, and Springfield. They are certainly better than Sig, HK, Glock, CZ and a whole list of others. They take care of their guns under warranty better than most. With them if you have to ship a gun back for warranty work they always pay shipping both ways. If you are having custom work or refinish work done on a gun they will send you a pre-paid FedEx label and allow you to ship it 2nd day on their account saving you $$$. When they can simply send you a part and let you repair something yourself they do it.
So because I expected a new gun to operate and be defect free I was like you're customers who expect free stuff. Had the gun worked and not been defective s&w wouldn't have heard from me. I wouldn't have had a reason to seek a new guide rod or ask for a gesture of good will when I have to wait 2 weeks for that part.
You seem to be missing the point a bit. They do not owe you anything more than a functioning pistol. Yes it sucks to buy a new anything and have it not work right out of the box but S&W is making it right by sending you 2 recoil assemblies. They are under no obligation to do more than that.
Perhaps some of you have never managed or worked in a customer service related field. In my experience both working and managing the cs rep should ask the customer "what can we do to make it right". And at very least apologize.
Now as far as the ridiculous blackmail/extortion thing since its been brought up again I pose this question. If you're at a fine restaurant. And you're food comes back cold, undercooked or overcooked and you ask for a complimentary drink in the meantime are you extorting them. Blackmail or extortion hinges on a threat of a negative outcome should a request not be met. Since no threat was made to s&w my request was just that a request.
You restaurant analogy also does not hold up. When I am at a restaurant regardless of price point if something is not to my satisfaction I bring it to the attention of the staff. If the error is bad enough I will ask that the item be replaced. They are under no obligation to give me anything more than I ordered. Personally 99% of the time at restaurant when I lodge a complaint about the food or service I state up front I do not want anything free. I am telling you about the issue I had so you can correct it and improve your business because if no one tells you that you messed up you will never be able to correct your mistakes.
You are mistaking people giving a restaurant or gun manufacturer the opportunity to correct the mistake with placating the customer by giving them something they are not entitled to. Not demanding free things does not make one a door mat.
You did not make an implicit threat to S&W when they did not give you "free stuff" but in a great irony or ironies you followed through as if you had. They did not give you a "free" mag so here you are trashing them. Unfortunately others are not seeing it the same way you are and you seem to be getting very upset about it. In the end 2 weeks is not an unreasonable amount of time. It once took Steyr 14 months to replace my gun. Colt took 10 months once. Did it make me happy no. Did I mention it if someone asked yes. Did I ask for free stuff????? NO.
Clearly you want free stuff. You feel entitled to it because 2 weeks of your life will be spent without a functioning pistol. I think that you should remember your desire for "free stuff" the next time your favorite brand raises prices on your favorite pistol because I hate to break it to you that stuff you got from Ruger and Springfield was not free. It cost them $$$ and you might not have had to pay for it but someone else will.
I personally would rather simply get the gun fixed and keep the price where it is and allow companies to continue to exists vs giving away the store over every little issue. YMMV