Here's an essay by me
I read the article and the short answer is yes and no. First of all - primes are not all that much cheaper. Just look at the limited lenses - hardly what I would call cheap at all. $500 for a DA70, dont even ask about the FA31, etc. He makes it sound like all prime lenses cost the $80 like Canon's 50mm f1.8 does. And I am comparing current prime's still in production here - not some old K that you can buy from ebay for $40.
Secondly, zooms are getting much better - not all zoom lenses are in the class of the DA18-55 and I tell you if my DA* 16-50 that I pre-ordered cant compete with say the DA21, DA40, etc. at the equivalent focal lenght and aperture I will be dissapointed. A DA* 16-50 is not (shouldt even be close) in the same class as a DA18-55. These top-tier pro-grede zooms should offer exceptional image quality. Sure a prime may still have a *slight* edge in sharpness - but how much? Am I going to sit and pixel peep the image I shot so that I can spot that oh yes I shot this with a prime? One area where the primes may be able to show themselves will be the bokeh, contrast, etc. - hopefully the new DA* lenses will be quite the performers in this area and according to Pentax and their claims they should be quite the performers indeed. Looking at past FA* zoom's also seems to suggest that Pentax (and I am sure others) know how to make a quality zoom - theres a reason they cost so much after all.
Dont' get me wrong I am all for primes and top image quality but to talk like some zooms cannot provide the IQ is stupid and a little naive IMO. I currently own the DA18-55, DA50-200, DA10-17 Fisheye, FA50 F1.4 and DFA 100 F2.8 Macro. Sure the FA50 is indeed my best lens but thats because the zooms I own are cheap kit zooms - I think this is expected.
What is going to happen when I eventually replace my two kit lenses with two DA* lenses: my lineup is going to be as follows:
DA10-17 Fisheye f/3.5~4.5
DA*16-50 f/2.8
DA*60-250 f/4
FA50 f/1.4
DFA100 f/2.8 Macro
This is all the glass I will need - it will consist of 2 high quality DA* zooms, 2 high quality primes and a unique and good fisheye zoom. I have no need for anything else and will the DA21 Ltd and DA40 ltd really make my pictures any better than what I will shoot with the DA*16-50? Will it even make a lot of discernable difference over the DA16-45 when printed and looked at on a 8 x 12 print? I doubt it for the top end and mid grade zoom and maybe yes a little better than the DA18-55 but I also expcet the two higher quality zooms to have a visible difference over the DA18-55 too (ie. vignetting, smoother bokeh, sharpness, CA, etc.).
It all seems a little sentimental and even more about bragging rights IMO. Maybe its just me but I agree with some aspects of the article but its a little misleading too. Do I really now need to go and buy say the DA70 Ltd? Will it make that much difference over the say DA* 50-135 at 70mm both at f4 or 5.6? I have a feeling it wont - especially for normal prints but it *may* if I pixel peep at 100%. What about portraits you say for the DA70 - well my FA50 is a whole 2 stops faster (the DA70 is really like an f2.8 not f2.4 - check to see comparisons to the FA77 to prove - it has been proven in both shutter speeds picked by the lenses and the DOF) and has beautiful bokeh and sharpness. Also the FA77 was an excellent portrait lens on film as 75-80mm is usually considered ideal lenght for portraits - well the FA50 now fits that bill at 76.5mm in 35mm terms). Also the DA* 50-135 is exactly the same speed as the DA70 Ltd (taking into account the DA70 is an f2.8). We will really see how much better the DA70 will be at 70mm over the DA* 50-135. At f2.8 it may have a slight edge in smoother bokeh and sharpness, it will probably be gone by f4 and beyond. Will any person be able to tell if an identical image is taken with the DA70 or the DA*50-135 at the same aperture on an 8 x 12 print. I doubt it. They should both provide excellent optical quality. They serve different purposes - the DA70 being compact, light and offering excellent IQ (at a price of $500) - while the DA*50-135 will offer excellent build and optical quality (maybe identical to the DA70 or maybe just slight worse off but excellent versatility (at a price of course of close to $1k) though of course be heavy and big.
In short - primes are primes, and they are all usually very good indeed be it a $100, $200 or a $700 prime (this is where I agree with the writer), however all zooms are not created equal - with a zoom its more a case of you get what you pay for and to offer exceptional IQ that is maybe on par or close to prime quality (with the added bonus of a fast constant aperture, build and versatility of top end zoom) costs a lot. Again, IMO - its a case of how good is the prime compared to the top end zoom and will you pay the price to get that top end zooms; IQ, speed, build and versatility. Compared to a lesser cheap kit zoom - the prime argument holds much more weight IMO.