The Disney adult of today is the worst. To them, Disney can do no wrong and is perfect in everything they do.
Yesterday's adult was no different than todays except that back then when we went we always felt that we got our money's worth. Yes, we had lines, but since it was just one, usually 20 minutes at the most popular because the damn line kept moving unlike today when you stand in the heat and humidity for sometimes more than an hour. There weren't more people there just was no "legal" line cutting. Every attraction offered that same first come, first served privilege and even new ones didn't have that backlog.
Fastpass1 was the start and even though it did cause longer standby lines anyone at least had that chance to get a FP that didn't break the bank of the people that lived on careful budgets. Apparently, before the system allowed you to not go to that one if the line was to long. You went to a different one and came back when the line was reasonable. We didn't feel like any of us were privileged and that Disney really wanted us to have a good time and then they could get their needed profit by many, many return visits of people needing to budget.
That might be the only real difference is back then Disney really did do no wrong and if they did they fixed it, if not immediately, then soon after. Those that are "worst", as you say, now are just unaware of what is missing now. Those of us that thought Disney could do no harm back then are the ones that are complaining currently. The adults of today just don't know any better so to them it is just magical. That is why nothing is going to get better, because those of us that do know better will be dead before to long just leaving those that have no base reference except of their own time and place.
The bottom line is that those of us that first started going in the 70's and 80's appreciated Disney for what it was and it was spectacular for the times. Today's WDW is more technically and physically attractive than back then but that is still spectacular to the new generations, but some of us know about how it once felt to go there that was way more important that the physical stimuli. 50 years ago it was ahead of the known technology, or an innovator that others were always striving to live up too. It's not hard for others today to not only meet it, but in many cases surpass it. Back then the decisions were made by the imagination of its leaders and not the pencils of the accountants.