I find that no less amazing than the fact that Cessna can still sell new 172s and 182s for the prices they do (and still manage to lose money on it), especially when you've got a number of alternatives out there that are higher performance and look cooler.
Remember that there's more missions out there than going fast. The 172 is a training airplane for the most part, and a significant percentage of 172 sales go to flight schools. The rest go to people who just want a dirt simple airplane that's easy to fly and maintain, and they just want to get up in the air and don't care that the plane is "slow" because it's still twice as fast as driving.
Likewise, the 182 is a heavy lifter, not a go-fast machine. Sure, it's faster, but it'll burn more fuel. However, when you want to take three of your buddies and their bags for a weekend trip, or go land at a 1500-foot unpaved backcountry strip, or fly for 5-6 hours at a time in comfort (nice upright seating position and wide cabin), or... The list goes on and on. Sure, it's not as fast as a Mooney, or a Columbia, or a Bonanza - But it'll lift a bunch of stuff into the sky, get off the runway in a hurry (I've flown off a 1000-foot strip in the 182. Yes, one thousand.), and take a real beating on some unimproved surfaces without costing you a fortune in landing gear maintenance. It's the best all-around plane, and by that I mean that it's good at the largest number of things. In fact, it's great at pretty much everything except for going faster than 145 knots, being super-efficent, and looking sexy.
The metal Cessnas obviously appeal to a large portion of the market - In 2007 they shipped 373 172's (133 R, 240 SP) and 301 182's (161 NA, 140 Turbo).
What amazes me further is that Mooney doesn't sell more planes
I'm with you there. I wonder if all the OWT's have hurt them over the years.
and that Lancair hasn't taken a bigger chunk out of the high performance singles market than it has. Looking at the value on, say, a IV-P compared to an Acclaim Type S (probably where the biggest market share is being taken), Columbia (yes I know it is/was a Lancair), and SR22 turbo, I know where I'd put my money.
Well, if you didn't have to BUILD the thing, that would increase sales by orders of magnitude. The other thing is that it's only two seats (how many certified two-seaters for sale that aren't LSA's right now?) and it is a go-fast machine that's challenging to fly, practically the exact opposite of the 182. The 182 can fit a lot more people's mission profile.
For example, my flying club has a Piper Archer II. I love that plane, and have put about 130 hours on it since the end of March/beginning of April. It really is a fabulous plane for a number of reasons. Yes, it's slow and not as efficient as, say, the Mooney or your Bonanza, but I can see why they've got their popularity.
Easy to fly, easy to maintain, hauls a pretty good load (ours are both at 1005 ±1 pound useful load, or 717±1 payload with full fuel, or 801±1 payload with fuel to the tabs), simple systems, etc. It's another good all-around plane, and IMHO has better ground handling and is easier to land than a 172.
I am, however, surprised that the DA40 (232 shipped in 2007) doesn't sell better than the 172 (373 shipped between the R and SP), and completely obliterate the Warrior and Archer (27 and 16, respectively). It's got all the same advantages (simple, easy to fly), full-fuel payload beats the new Archers by over 100 pounds, it's a good solid 30 knots or more faster, and it definitely is a lot sexier than the old metal birds.
We also have a Piper Archer III that is in the process of being rebuilt and will become the replacement for the Archer II once it is finished. Last night while I was in the hangar, I went over and looked inside the interior of the Archer III, and was I ever impressed. Comfy leather seats, a truly new looking interior with dual 430s. I could see where someone looking at the new Archer III vs. buying an older Archer II or Cherokee 180 would look at something like that and say "Yeah, I want the new one." Personally I wouldn't do it, I'd buy the older one and update it if I really wanted that (and I'd not have dual 430s, but that's just me).
The problem with the new Archers is that they've gained a lot of weight. The useful load has dropped by nearly 50% compared to the late-70's ones.
The other question is one of maintenance. You pointed out a used King Air for about the same price as a new Seminole. I'm right there with you on that, and if I had the money I'd absolutely go out and buy a used King Air. But for a lot of people, I could see where having a used King Air and the associated potential maintenance issues and costs becomes less attractive than having a new Seminole, where the thing is simple and everything is new so you should theoretically not suffer as many problems.
I doubt there's very many people, if any, were considering a used King Air and decided on a Seminole instead. Completely different missions, again. The King Air carries a lot of stuff and goes fast. The Seminole just sits on the ramp at the flight school and dreams about being able to climb on one engine.
As am I. That means in 30 years they'll be around for you and me to buy.
It's just too bad that most of the planes that I would most want to buy were discontinued in the 70s or 80s with no real replacements having come up since.
So, which planes are you speaking of?