And as a hobby dieter & big loser: Once you realize diet is something requiring long-term conscientiousness, the truth and enormity of the change can hit very hard. It is an emotional roller coaster that can just as easily make people more fat than when they started.
Should we also give free houses and luxury cars to people who refuse to work?
I know you meant this as a rhetorical question, but yes, I think society should provide free basic housing for those that can't afford it, whatever the reason.
The difference is crucial.
Is it true that you have to work, put in effort for most things in life? And that people need to learn that? Yes.
But isn't it also true that the science is largely an endeavor of decreasing the amount of work people need to put in to achieve the same result in some area? If you look at almost all of the history - that is also true. This is just another installment of that same centuries-old trend.
Science wants (and should rightfully want) to make a pill that will make something require less effort (staying healthy for long time). If some people would not put in the big effort, but would put in the small effort, given the opportunity - than all the power to them. It's the ultimate goal of science anyway.
Take Type 2 Diabetes. Science is putting a significant amount of time and money to "cure" it. The sad irony is, we have a cure. Yes, that takes - evidently - too much effort. But isn't that a matter of perspective?
Cancer is also a byproduct of diet and lifestyle. Seems to me that cancer is more difficult than changing diet and lifestyle.
The point is, science is forced (so to speak) to seek things that are already found. "Easy" or not, what other unintended consequences does "easy" create? Science should be seeking best solutions, at which point it could move on to other things.
What else do you propose the science be directed by? What else is really there? Are there any other real reasons for science at all?
Science is for us, the humans, the society. Studying things with no reason or benefit for the society, somehow detached from humanity, for what, some vague abstract reasons? I'm not sure I would want to put my effort into that, either in the specific sense, or even in the more implicit sense of funding it through my taxes.
Doing science for the sake of science? What's the point?
Looking at the question from another perspective though - I think a good direction for science would to study how would it be possible to make people take the extra effort, make the difficult choices - that would lead to a natural resolution of many of their problems (like exercise would lead to less cancer). But in this specific case, stopping science from looking for anti-cancer pills, for example, does not seem like a proper way to go. Willingly preventing progress in making lives easier with low-effort methods like pills (if they really do work) does not seem like the best way to promote otherwise healthy behavior.
The answer is obvious yet you're not seeing it.