Why not?

Wouldn’t they be in the best position to test or design the optimum cable for their component?

Yes and no. They could pick the best PC that works IN THEIR SYSTEM, but that’s in no way a guarantee that it would synergize best with a customer’s specific needs. Given how cables can sound different in different systems and the quality of power, power conditioners, etc. varies greatly in every system there’s really no “one size fits all” solution for cables and why 95% of all manufacturers don’t include PCs or interconnects with their equipment. If the cable qualities were consistently translatable they’d include or at least offer them. Making cables optional is a thought, especially if they can be offered at a discount, but most seasoned audiophiles won’t do that as they know what cables work best in their systems and will in all likelihood stick with those. Obviously including any quality cables would jack the price up of any component dramatically after retail markups and make them look much less competitive compared to those that just provide a passable cord and let the customer decide where to go from there. If it made sense to offer better cables with their gear manufacturers would be doing it, but they clearly know it’s to their disadvantage to do so unless they’re in the cost-no-object category where they can bury the cables in the astronomical cost of the equipment.

I completely disagree with ‘deserve your attention’ notion. When I am shopping for electronics, I am considering its features, design, implementation and how it’s going to sound in my system. I didn’t buy my $25K EMM Labs DAC because they included $200 Kimber Power Cable which I did not care to use, instead I used a $5K PC. 

@lalitk Bingo!  A perfect example and case in point.  

Why all the back and forth?  Just try some better power cords — either buy used and sell at little/no loss or buy direct from the many direct sellers and take advantage of their generous trial/return policies — and if they don’t make a significant improvement stick with the generic PCs and live happily ever after.  What I can’t accept is when people just reject out of hand PCs can make a difference and never even try better cables yet preach that better PCs can’t make a difference because there are no measurements to support it.  That’s just willful ignorance, and as @ghdprentice as a scientist has stated and while he might not fully understand why PCs make a significant difference, in reality they do in his experience for whatever reason.

Bottom line — not everything is measurable relative to what the human ear can hear.  So for those of you who follow the dogma that PCs shouldn’t make a difference, you’ve got no excuse as it’s free, or very near free, to try several brands and use your ears to see if they make a difference.  If they don’t, then fine you’re right where you started from with some good personal experience to support your beliefs.  If you haven’t yet tried better PCs, what are you afraid of — that your preconceived world might be upset and you can’t explain why?  Who cares?  If you get better sound you win whether you can explain it in measurements or not.  Sheesh. 

As a scientist I can understand that if one shows something happening on a DC supply then I know that the cord changed things.

@holmz Ah, I see.  You don’t trust your own ears.  Got it.  You and @ghdprentice would have an interesting conversation as two scientists with polar opposite views on cables.  Why not just try an aftermarket PC just to see/hear for yourself?  What are you afraid of — that your comfortable and convenient world of theories and measurements might implode if your ears tell you they’re hearing actual improvements?   Or maybe you won’t find any improvements or maybe even decreased performance.  Either way, that’s called learning — a concept I’d think a scientist would embrace.  

@holmz I said…

— that your comfortable and convenient world of theories and measurements might implode if your ears tell you they’re hearing actual improvements? Or maybe you won’t find any improvements or maybe even decreased performance. Either way, that’s called learning — a concept I’d think a scientist would embrace

To which you reply…

What you describe is not “learning” so much as its is “experiencing”. What would I have learned?

Wow. Just…wow. If you’re saying you can’t learn through new experiences we are truly on different planets. I’ve learned a helluva lot more by keeping an open mind and listening to lots of different equipment than I ever learned by looking at measurements. At this point I’ll take @thyname advice and just give up as there’s clearly no point going any further with this and leave with some Pink Floyd lyrics that seem appropriate…

The bleeding hearts and the artists make their stand
And when they’ve given you their all
Some stagger and fall, after all it’s not easy
Banging your heart against some mad bugger’s wall

With the power cord all we have some testimony that someone believes it works. So we know that “they think it works”… in their place… with their gear. But that does not tell us if it work on our gear, with our place in the power grid.

@holmz Hence you yourself have just presented the perfect rationale for trying a PC in your own system, but you refuse to do that for some reason. Whatever. To each his own. Peace out.