Pah! Distributorless Volvo?!!! Go wash your mouth out with soap sir!!! In fact, I consider that comment bordering on the "ad hominem" and have a good mind to report you to the moderators!
Volvo, indeed! No, in fact my 19 year old quarter million mile monster is that paragon of build quality and reliability...
..an Alfa Romeo!!!
(Surprised? I certainly am)! This was a £300 car 5 years ago and has been utterly amazing in terms of reliability! It's one of those cars that has earned it's place in the garage 'til it rots now. (which is probably what will kill it off, ultimately)!
As for the balance between maintainability and features/performance peaking some years ago, well, even in my experience people having been saying that for 20 years or more now. Ever since the demise of the carburettor! If I was older, I might even still know a few people who didn't trust hydraulic brakes! My dad is a mechanic and he says he's glad that he's going to be retired soon. The cars are getting too complex for him to fix. However, I think it's largely just a different mindset that is required. As well as the trusty socket set and big hammer, today's DIY mechanic needs to cash out on some computer equipment and learn a different set of skills (or maybe an additional set of skills). If anything, it's getting easier with greater standardisation of engine managment fault codes on the most recent vehicles.
I accept that there are plenty of disadvantages too, though. That said, by and large (and I choose my words carefully here!) "design faults" are getting fewer and cars are getting more reliable. When I first started maintaining cars, it was (I think) easier to get a spare from the scrapyard because quality control was worse. Chances are, if you found one in a scrapper just like yours, the part that you needed would be OK. These days, I'm starting to find that one disadvantage of highly automated production techniques and better quality control and consistency of manufacture is that "...they all do that, sir" - so if you find one in a scrapper, the bit you were after is much more likely to be knackered too.
That, of course, is a two-edged sword. The advantage is that (especially with model-specific internet fora), exchange of information is much easier. I can hop onto the forum and ask about a problem and there's a pretty good chance someone else will have had the same thing.
By the time my wife's car is 20 years old, I imagine that if the £1000 filler cap ECU is a common issue, someone will have copied it and be making them in China for about £20. I'll probably even be able to order one online! If it's not a common issue, there will be plenty of intact ones in the scrapper!
As for bumpers, I must admit that I've never really found it a problem. I'd never buy a car I didn't like the look of so that's more important to me than being able to knock the corners off it and replace them easily. (I did once have a Series II Landie though, and it would fulfil those requirements PERFECTLY! Cheap, easy to replace and nigh-indestructible bumpers; amazingly cheap and plentiful spares that took minutes to fit. Only trouble was, the 15MPG and the ride that would leave you in need of a good osteopath after about 20 miles)!