To be fair, most classes stand a fair chance of dying at low levels. A cleric with d8 hit dice has as much HP as a monk or ranger, and more than a rogue or bard would.
Problem being a Cleric is this small thing called...you're expected to be a team player. If you don't heal the rest of the party up, typically they'll either kick you out of the group...or kill your character and have someone else who is a team player be the healer...with or without you.
It's sort of like how people expect the fighter to go up and fight things, perhaps even protect some of the other characters and that the mage will actually cast spells that hurt the enemies and don't target players.
Teamplayers and all that stuff. Which is why I find that MANY don't like playing the characters with healing capabilities...the rest of the party expects them to use it to help the party out. It's a team thing. In fact the team thing plays into the dynamic of why some play melee instead of casters.
THAT'S ONE BIG REASON some don't play casters, especially at lower levels when most can't be the big one shot themselves and spells are much more limited. They are expected to do certain things, such as the cleric or even the Druid (or if no one plays those...in 3.X the Bard) to be the healer and use their valuable spells healing up the party.
Or, for the Mage to be able to do certain things with their spells such as take out a large group of bad guys in at least one encounter...
Or the Bard to do something that benefits the party...
Whereas a warrior, except for having to bash bad guys...typically can be a tad more selfish and do what they want...not as many party expectations. Still have to be team players...but they don't have to expend much of their daily power to be one.
I suppose that means at lower levels at least...that the warrior types have more freedom in what they are expected to do.