I'm confused about the OP. Are you really an 'oldster'? How do you define an 'oldster'? You say the new rides are too much for old people, but then you admit it's the 'oldsters' that pay for the family trip. Hence, by mentioning family trip, one would assume you mean 40 to 50ish age range. Being a 40 yr old married to a 48 yr old, we thoroughly enjoy ALL the new rides. We both have weight issues, so it's not like we're in tip top shape. We had no problems with anything at WDW theme parks.
If you're truly older, I don't know if that many grandparents pay for the family trip any longer.
Now, if you're simply bemoaning the loss of a loved memory ride, then I understand your point. I miss the submarine ride as well. I go on IASW on every trip for the nostalgia. But we must allow for updates, which include the new trend of thrill rides. If we left the park stuck in the mid 70's they would lose money because our families wouldn't want to go there. Mom and Dad's favorite vacation place would have become stale and boring. A wonderful trip down memory lane for us and a drag for the kids. (I hope that rambling makes sense.) And remember, they did just do a whole new update on IASW - that couldn't have been cheap. But they didn't take away a traditional ride there. (as far as Spaceship Earth goes, the last 3 times I've been on it it has stalled for 20-40 minutes inside as it broke down for various reasons - If not replaced by another ride, it certainly needs a MAJOR overhaul. That's a little TOO tame for me - sitting for 20+ minutes staring at the same diorama. And no, I'm not talking about a brief stall to let a person on/off that has mobility issues. We're seriously talking 20-40 minutes - the 40 minutes was this past may with our 18 month old infant...boy that was fun...NOT. He totally didn't understand why we were sitting in the dark not moving.)
Both my DH and I feel there are a nice mix of rides and attractions.