If you gave me two Tomb Raider games, both exactly alike in content outside of a Lara Croft in one that is athletic, young and attractive vs one that is middle aged, unfit and overweight, I would choose the former. I'm guessing most people would be the same.
The stunts that the character pulls off simply wouldn't make sense otherwise.
Considering what I said above about having to accept fitness does align with the feats these characters pull off your example might be better phrased as a Lara with terrible acne, hair loss/receding hairline, ragged teeth (maybe missing one) and some sort of non-symmetrical facial features (lopsided eyes/nose or something bent/misshapen). You know, things many people have to handle in the real world with gene pool diversity. Of course, some get handed pretty damn good genes and I guess devs could just say well, Lara is one of those lucky few!
However, it's rarely going to happen as in most games of this magnitude (large scale adventures with action/dare defying stunts) the overall package is gong to be draped in all the hero and fantasy tropes around. All to try and create a sum of its overall parts, that markets well, is remembered and equals if not beats the other games with "perfect" heroes/heroines. So it's not just that Lara conveniently has the gene pool to back her up, like every other big character/actor and so forth, it's playing into psychology and behavioural reasons a large generalised audience WANT their fantasy heroes/heroines to be almost
perfect. Real life and all its miseries are boring and/or what people need to live with in daily life. Fantasy is often escapism. Like it or not an everyday Lara or Drake with serious ill health, a lack of "objective beauty", irritable bowel syndrome, some complex mental illnesses and boring, drab and mundane personalities would not market well, would probably sell less, and yes, people would even be like are these the heroes we're playing as/aspiring to/escaping reality with?
Hey, it might make things more interesting if Drake had to shit in the bushes every 30 minutes, but yeah, idealised tropes around heroes exist for a reason, in all mediums, even actual acting where nearly every damn lead actor is objectively beautiful, well groomed and has to have somewhat of a personality mixed in with confidence (or the trope of lacking in confidence to being a bad ass confident individual by the end of the film). Holywood and other mediums rehash a lot of the same tropes and stories for a reason, they sell. Like every damn hero comic/show/movie in existence (if they're done well).
Nudity, titillation and sex plays a role in this and is it any surprise those getting naked or having sex are often 9's or 10's? How often are you seeing Donut Drake get his penis out and have at it with the ladies? Yeah, rarely. Best bet for that might be a comedy, but even in comedies, there is often the trope of "ugly nerd" turns into beauty. Often by removing glasses (or replacing outdated glasses), having braces taken off, and straightening hair rather than leaving it frizzy. Not to mention dressing better, at times often proactively sexual rather than draped in a baggy outfit your Catholic grandparent used to wear. These tropes and fantasies repeat themselves over and over and over and over... and still get consumed over and over and over. New generations of minds and humans still chase after what the aging generations did/still do. Until evolution stops us being a sexually reproducing species (which I don't think it ever will), the human mind will continue to be excited and stimulated by sex, sexualisation and fantasy tropes that allude to things the average person may be missing in their lives.
Sex can often be fun, cheeky, rude and in your face too. Tying into having a personality, being provocative and actively trying to be mischievous. Again, often fantasies that humans like to engage in if not think about. Life being exciting and flashy is often what many want, rather than the mundane, the robotic and the safe. How many adults do you think end up in counselling of some sorts for having a "boring" sex life? Yeah, it happens all the time. A big part of that isn't just trying new things, it's approaching the ordinary with a different attitude, fun, and possibly being a bit more cheeky or outgoing. This often comes across in character behaviour or design, think Bayonetta. To instantly think that is crude or childish is okay to jump to, but thats reason again lots end up in therapy due to their sex lives. It's often precisely because some excitement, crudeness and immaturity/laughter is missing. Not to say Bayonetta is a damn cure for that, but to highlight part of the reason she was written and idealised as she is - The mischevious, outgoing, risky, confident and provocative tropes many wish they could aspire to in their day to day life (if not sex life). Why do you think so many damn women want to cosplay as Bayonetta and idealise her?