For the same reasons why people don't complain about John McClain surviving the various physical stunts he undertook in Die Hard, but find the villains in Die Hard 4 to be completely unbelievable in the amount of punishment they take.
1. There's an overall degree of verisimilitude that permeates Raiders, and which (I gather) is lost in Kingdom.
2. The latter films make use of CGI to actually show you how he survives, instead of implying it and letting your mind fill in the blanks. That means your mind is forced to confront the unreality of the situation, instead of being able to just kinda skip past it and move on to the next scene. I actually think Raiders works better because you don't see the deleted sequence of Indy lashed to the periscope. But you can't not see the "nuke the fridge" sequence, so you have to mentally deal with it, and it's a lot harder to excuse it away based on what you do see.
3. The degree of unbelievability is much higher in the latter films. I mean, it's unbelievable in any case, but within the film universe and the in-universe "rules" established about what Indy and McClain can endure, you accept the earlier films. Both heroes take punishment and show it in a way that heroes in other movies might not, which is where the "verisimilitude" comes in. We expect our movie heroes to shrug off stuff that would take out a normal person; that's what makes them heroes. What makes Indy and John McClain heroes of a higher calibre is that they don't merely "shrug off" injuries, but rather persevere in spite of them, which makes them appear more heroic. But all of that is different from when people survive stuff that is patently absurd, like literally being hit by a car or cooked by the heat of a thermonuclear blast inside a lead-lined refrigerator while being hurled through the air and impacting on the ground multiple times and then wandering out to witness the mushroom cloud and take a deep breath of nuclear fallout. There's "suspension of disbelief" and then there's "complete and total bulls***."
4. The original movies are simply better, more entertaining films. In general, people overlook the stuff that might bug them (plot holes, inconsistencies, silly bits, etc.) if the core film itself is entertaining. They forgive a film's flaws if they're already entertained because they just aren't paying close attention to them. When a film isn't entertaining, for whatever reason, the flaws are more noticeable, because your mind is already disengaged from the film itself, and instead is "present" to nitpick things. The things we nitpick frequently (aren't the real underlying problems with the films; they're the things we noticed because of the underlying problems with the films. ANH has doofy, silly, or poorly written or performed moments in it, but we ignore those because it's a great movie on the whole. TPM? Not so much. Although, to be fair, in TPM's case, I don't think there's any way to "ignore" Jar Jar.