If I summarize and say simple is better I think we are on the same page, although it is possible to build reliably at higher power levels. Exactly what tuners have been doing for a long time. Take a motor, add boost, blow motor, rebuild with something beefier and try again. No matter how you spin it at some power level things fail, but finding what fails allows you to then build beyond that. The only manufacturers can learn this is to try it. Regrettably this means that we the consumers are now more beta testers than ever. Moving to the category of I don't want a first generation of anything. It used to just be a first year, but now it is a complete generation.
Good example of power building is just looking in my garage. My 600cc snowmobile that stock is around 120hp is sitting well over 155hp now. No forced induction and a 30% gain. I don't expect to still be able to get 10,000 miles from it before rebuilding, but 5k is absolutely no problem. At that point I'll just drop in some fresh pistons as they are what tends to go. Found the weak link and dealt with it. Does cost me $80/piston though.
Long term I am fine with the downsizing AS LONG as there are still options for the enthusiast cars. A strung out 4 banger with no room to grow doesn't work for me as manufacturers typically choose to release things with 30-40% less power than they should have.