D&D 3.5 and Pathfinder (and older editions to a similar degree) are built around the notion of, "If you fail a save or if you take a good ol' hit or two, you're dead, KO, or screwed!" This applies to you, your partymates, and creatures out of the books.
Why?
Why this emphasis on one-shotting or two-shotting something?
For fun.
In the Safe Game a character is immortal, protected much like a cartoon character or pg-13 or below character. They can get knocked around a bit, but nothing will ever happen to them....ever.
In the Deadly Game a character can die any time, any place and any how. Unlike any form of fiction.
Now lots of people like the Safe Game. "Oh no the dragon knocked me down! I'm like so scared!'' They like the idea that they are immortal and nothing can happen to the character...ever. But after a time, some people get bored with this type of game. ''Oh, yawn, more demon lords? Oh they trip my character and do like five damage, wow!" After a while it's just no fun to always auto win...though some players will always like the easy button auto win. Victory without the chance of failure is hollow.
But for a different game experience, lots of players turn to a classic Deadly Game. It's nothing like a Safe Game. In the Safe Game, the beholder just uses it's lame 'wound' eye...but in the Deadly Game it uses disintegrate. I've converted tons of Safety Players to Deadly games. It's a common theme: After they play their 100th or so auto win Safe 4e game(or whatever), they get very bored. That is where I'll get them to play in a Deadly Game, and the shock and transformation is amazing.