This is a reasonable question - we might have found some sort of "no free lunch" theorem! But as others have pointed out, so far no such inevitable tradeoff has been found, which in itself supports the view that it won't be.

There is Mikhail Blagosklonny's theory of programmed aging, in which aging is a byproduct of helpful developmental processes. This does seem to imply we need to mess with some pretty fundamental metabolic processes (hence mTOR inhibitors). That's close to what you're suggesting, but it still seems achievable.

Since all organisms are made of somewhat-similar cells, the bristlecone pine, the immortal jellyfish, long-lived tortoises and so on, are all important existence proofs that negligible senescence with no ill-effects is possible.

As they say, the goal is to die at age 150 with the body of a 30-year-old in a freak skydiving accident! It's been good to see longevity research move decisively out of crank territory in the past 15 years.