I don't think it's reasonable to complain that you can't sustain a family and a house that is 1.5x what they were in the 1950s, on a single income.
However, if you go back 50 years earlier, the lower class lifestyle was not that different from the favella living in slums around the world, where entire families lived in one or two rooms and everyone in the family who was able was responsible for contributing to making ends meet.
Your second point (which I agree with) seems to imply that the US standard of living peaked in the 50's
The lower bound on lower middle class is, according to Wikipedia, $32,500. There are plenty of houses available for purchase in the $60,000 range, which is well inside of affordability ranges.
There are a plethora of rural homes available within those ranges, but that level of income isn't necessarily exclusionary to city dwelling either. Dallas, San Antonio, Cleveland, Cincinnati, St. Louis, Tampa, etc., are all very affordable, and at least according to MSN[1], has homes available for less than the lower bound on lower middle class.
[1] - http://realestate.msn.com/what-you-must-earn-to-buy-a-home-i...
> The lower middle classes can't own any house at all with just one wage earner
is not a true statement. If you'd like to qualify it further, feel free. I suspect I'd have to research more to answer, and I don't necessarily disagree with the sentiment you're suggesting, but presenting falsities as facts doesn't do any argument any particular good.
Similarly, the 'sane working hours' you mention, generally speaking, were 48 hours a week or more. In the 'upper' middle class, more hours were spent at the office as well. Today, the average worker works ~37 hours.
Assuming job accessibility (which I have no idea if there's a guarantee of or not), and more reasonable home purchasing, I think it's not "simply false" that one can live the same way as they did in the 50s on the equivalent working wage, one simply has to make more apt comparisons to see that the goal posts have shifted.
The average 1950s family only owned one car, while the average family of today owns more than one (likely, to support the second job). If each of us bought houses half the size of what we're currently buying, and half the cars, we'd likely be in greater parity with our 1950s brethren. Also, they had to pay less than half of what we did for college, and they also likely didn't borrow in order to afford it, which factors in even further in measuring debt load.
Anyway, I think your comparison is somewhat rose-colored.
Actually, it's an even greater difference than that. The median household income in 1955 was about $4k, while today it's about $50k. In 1955 the cheapest Ford cost about $2k, or half the median household income, whereas today the cheapest Honda costs about $16k, or a little less than a third of median household income.
If we just leave it at that, it sounds like things are about the same. However, the cheapest Honda today comes with airbags, air conditioning, power windows and locks, an FM radio, and a whole host of other features that were luxuries reserved for the most expensive cars (if they were even available at all). On top of that, my (and others') experience with modern Hondas is that they can easily go for 200k miles without major repairs or tune-ups, whereas 100k miles was considered a major achievement for a Ford of that era. Realistically, this difference in longevity alone means that a car from the 1950's cost about three times as many working hours as a car of today.
Beyond that, cars were still a relative novelty in the 50s, and ownership was more sparse. I'd have to research to see, percentage-wise, what the cost equated to. It's possible that their rarity meant that purchasing one car was equivalent to purchasing two, in today's age, but again, I don't have figures on that.
And, of course, I think you're dramatically underestimating the role of gender equality on the work force. Women work, many times because they choose to, not necessarily because they have to.
Regardless, the point you made simply isn't supportable by the raw facts that you presented, nor were necessarily the facts that you presented even factual. I don't disagree necessarily that the upper middle class of today is disadvantaged relative to the upper middle class of the 50s, but if that's the case, it's not because they worked less hours or owned larger homes.
I think in some ways, even the poor are better off. In some ways, even the wealthy are probably worse off. I agree that any notion of "We're all {better|worse} off than 1950" is naive without a greater degree of specificity. It's equivalent to saying that football was "better" in the 50s. How? Certainly not in player safety. Certainly not economically. In pure terms of game play, what metrics? Certainly not in passing. Etc.
It's simply false that you can live this way today on the same dollar amount.