Every action in the known universe (and surely in some unknown ones too) results in a trade-off. This is maybe the only precept on software architecture that doesn't "depends" on anything and is closer to natural law.
Human body isn't exactly bottlenecked by energy availability. Calories are getting cheaper and cheaper, with obesity rates as a testament to that.
There are old people who remain lucid and active well into their nineties, not getting dementia or cancer - through some combination of good luck, good genes and good lifestyle choices. They live a good life - until a stroke cripples them, or the heart fails them, or a very mundane illness like flu puts them in bed and they never quite recover from it. If that couldn't happen to them, how many more good years would that buy them?
Any treatment that addresses the aging-associated systematic decline in bodily functions should be extremely desirable. Even if it wouldn't help everyone live longer, it would help a lot of people live better lives nonetheless.