Quality issues aside, the biggest problem with McMansions is that they are trying to be something they aren't. They take all these different cool features from other eras and then jumble them together with unskilled workers who can't possibly come close to recreating the original detail. They are the hipsters of the architectural world.
Not justifying anything, but quality materials are incredibly difficult to find, and finding the labor or workmanship to apply the materials is near impossible in this day and age.
I'm going to have to disagree about the cement board siding. My house originally had shiplap wood siding but the previous owners messed it up so bad, it was unsalvagable (God knows I tried). While I think the original siding is preferable, I put Hardie Board on my house for a couple of reasons and I really struggled with the decision.
1) It is fire and termite resistant and in the hot summers aids in insulation.
2) This was my biggest reason. The wood of today is not the same as the wood from before. Wood from 75 years ago is much more dense. A stud in my house has about 33 rings that can be counted from the 2" side of a 2x4. A stud bought from Home Depot has about 7 and weighs about the same as balsa wood
I did get some real wood shiplap siding to put in one small place that isn't even exposed directly to rain and the wood warped. I remember reading that cement board has actually been around for a while (~100 years). It used to be used with asbestos and now uses cellulose fibers to hold it together.
3) It holds paint very well. Paint today is also not the same as from before. Formulations have made it less "toxic" but you need much of it to make it last as long. If you want to properly re-prep your house every 5 years to repaint it, a newly painted surface should look brand new still.
4) It doesn't have to look bad just because it isn't wood, but for the love of God don't try to pretend it's wood. I ordered the smooth cement board and actually had to special order from the factory because it was such an "unusual" request.
5) This is more of a side note, but the cost is actually a little bit more than actual wood.
Not all newer materials are bad, just 95% of them. I'd say the following are okay to use and have a purpose (off the top of my head):
2) Vapor barriers
3) Cement board, you can also use it under bathroom floors and shower stalls behind the tile. The bathroom in my house when I bought it had dryrot all around.
4) Paralam for large spanning joists
6) Electrical wiring
7) Some types of caulking, putty, sealers, etc.
Yeah, the really old, thick stuff is really neat. The newer stuff they call linoleum at places like Home Depot really isn't the same thing. If you want the same type of stuff from back in the day look into a product called Marmoleum, which is actually more costly than real wood flooring.