I think we need to separate fact from opinion. Comparing the current Fromme trail map with this one from 2003, the following Advanced to Extreme trails have been lost:
Walk in the Clouds
The Flying Circus
Jerry Rig and 38DD aren't on that 2003 map, but they could be added to that list (maybe there are others as well?). You could also say that trails like Natural High and Digger are due for a difficulty downgrade. I've only been riding the shore since October (although I've been dreaming of it since the late 90s), so besides a few of those trails that I recognize by reputation, I have no idea what most of them were like or why they were closed. Regardless, this confirms that there has been a net loss of difficulty on the shore (or at least on Fromme). I don't see how you could look at it any other way. Is the gnar still out there as some people say? Sure, but only a fraction of what there used to be.
How much that matters is a matter of opinion. Climbing trails, technical XC trails (eg. sticks and stones), parking lots, blue runs, etc. make the shore far more accessible and I think that's a good thing. It legitimizes the sport and the more people we have out there riding bikes the better. There are only so many resources to go around, and it would appear that the NSMBA's recent focus has been on accessibility above all else. Considering the focus in the past seems to have been about making super gnarly trails above all else, it's probably not a bad thing to spread the love around. Having said that, I would like to know what the NSMBA's stance is on preserving, resurrecting or creating new challenging trails. The lower end of the spectrum needed some love and it got it, but the current trend of losing challenging trails is pretty damn scary.