Well, Walther now has how many different polymer framed striker fired guns? All of which share zero parts? What major police departments are using them? I believe US SOCOM universally adopted Glock19's a couple years back and have been using them for well over a decade. Don't tell me it's "because of price". All manufacturers play the price game, it is a business afterall.
Glock is in Gen 5. With nearly all parts being interchangeable between generations 1-4, I don't see the generations being a "redue" so much as minor improvements. The generations of Glocks also has to do with patents. The Gen 3 patent has run out which is why you now see knock off copies. By changing some bits and pieces Glock retains the patent to the most improved version and keeps the knock off companies at bay.
HK uses stepped chambers, and a buddies SFP9 and P30 will not cycle steel cased ammo at all. The performance gain is all but non existent.
Glock has been using poly rifling since day one. They've only recently changed(not for the better IMO) to the "marksman" barrel.
Sight replacement is easy on any pistol with a dovetail. This new Walther uses Glock sights, so no difference there.
Glock grip angle is absolutely ergonomic. The more upright fist angle seen on other guns is not natural.
Stainless slide.... So what.
Tennifer finish(I believe it has changed as the Tennifer process is deemed environmentally unsound) is great, and has been used on Glocks since day one.
Accuracy has more to do with the shooter than the gun.
Sir I kind of figured you didn't know what you were talking about when you said the Walther's were a fail then you go and prove it.
The Gen 5 Glock has a new slide, new frame, new barrel and a new trigger group. I guess there are some parts there that are interchangeable but I rather think it might be limited to the springs. The design was badly in need of a make over. The Gen 4's at the range in Vegas had their slides cracking both in the front and rear. Compare the Gen 4 slide to the Gen 5 and you will see Glock has added metal in both areas.
The Glock had regular rifling that has the flats rounded. The Walther and HK's have true polygonal rifling. Do some reading.
Gee you have a friend who buys cheap steel cased ammo and it won't work in his HK wow. If you can't afford semi decent ammo why bother with a HK. As a reminder we are talking about Walther's. The Walther pistols are noted for their accuracy in a very crowded market.
The Walther uses Tennifer because they are made in Germany. Your Glocks are made in the USA and cannot use Tennifer due to US enviro legislation. Glock stopped using the finish mid way through the Gen3's. They use the same stuff as Smith uses on their M&P's and it works well. The slides rust big time in salty environments. There is a thread here about a guides 10MM Glock's bouts with rust. You might want to read it. Way tougher use than any of us will encounter. Please don't claim carbon steel resists rust better than stainless. It doesn't.
On sight replacement you really have to be kidding. I can have both the front and rear sights off a Walther faster than it takes you to find a brass punch and hammer. Walther's use polymer sights of their own. I doubt they use Glock's. I don't think my Walther rear and front sights are in a dovetail. I know the front is held on with a screw.
Glock's are in the hands of a great number of Police Depts. and some Military groups. Why the LEO interest. Money or the lack thereof. Glock bought most of their LEO business by under cutting their competition with a product that was simple to use, reliable as most pistols are these days and the guns work. Most police pistols ride in a holster for 30 years than go to the next officer.
Most civilians can buy what they want and what their wallets will endure. I think that is true of most here. A lot of us buy our guns to meet a specific sports requirements. The CZ Shadow2 and the more expensive Tanfoglio Stock111 are two examples of guns that are designed for competitive shooting and in particular IPSC Production. You won't find to many CZ and Tanfoglio shooters pinning/wishing they had a Glock in there hands when they walk up to the line. Others, and they are the majority buy their pistols to plink with. Glocks are great plinkers. The Glocks also do well in IDPA along with CZ's, M&P's, Sig 320's, Walther's, Springfields, Wilson's. Nighthawks, Norinco's, HK's and Rugers. NOTE TO Readers: If I left your favourite blaster off the list PM me and I will add it to my post. All those guns are found at IPSC matches as well. They are all reliable, shoot as well as the guy pulling the trigger and none of them are fails.
Take Care
Bob
ps In your post you forgot to mention the legions of after market parts the Glock attracts. My retort would have been because the OOTB Glock might need them. :>)