Why do you think they also have a +2 to Jump and Climb?
Because their muscles can give them more power output per pound of body weight.
By rights, it's Dragons that should be breaking their own bones and tendons by flying or even jumping up and down. But, because it's fantasy, I overlook that.
Human children generally don't have their muscles fully developed, therefore we don't usually see freakishly-strong children. Correct me if I'm wrong, but don't people with Dwarfism generally possess particularly strong upper-body strength with respect to their size?
So, halflings with an 18 STR don't freak me out. I used it to good effect in one D&D campaign a couple of years back, when my halfling fighter was able to maneuver around sprung pit traps in doorways just by LIFTING himself around the right-hand side of the entranceway.
What is the heavy load for a STR 18 halfling? 225lbs I think. So if he's a buff halfling of 40 lbs for example he can lift 5.625 x his weight! That is clearly superhalfling strength. This is really annoying me in an anal retentive way. Kind of like the whole mini-elf halflings in 3e. The picture of a halfling in the FRCS is almost the size of pixie or something. Thick hobbits could be a little stronger since they would have a lot more mass but still....
I think my mission after this campaign is over will be to rewrite a few races and institute racial max's for str and other abilities similar to the 1e style. Make a more 1e/3.0e hybrid. It's will be 1.847e.
Eh, it's fantasy. I don't worry about it too much. Now, if you can produce a real life halfling for me, I'll agree that we need to alter the D&D racial stats.