When people give female characters hourglass figures, do others automatically ASSUME they are trying to use sex to sell cartoons?
That would be about the size of it. Take a look at advertising, films, television, the supposed desire of all men is the perfectly shaped female with the hourglass figure, it is said to turn them on. In fact, in olden days, women learned the best way to get husbands to help in kitchen chores (cooking, cleaning dishes, pots and pans) was by placing several hourglasses strategically in the kitchen. When floors needed to be scrubbed, they would place an hourglass upon the floor and attach a chain to it. The husband would be down on hands and knees merrily following the hourglass across the floor as he scrubbed and scoured as the dutiful wife, yanked the glass, tugging gently at the chain. From this we achieved 3 things.
1)men with strong arms
2)high sales of hourglasses
3)the popular phrase "yanking your chain" which later men took to the level of meaning the wife was yanking their masculine chain (their wiggler). Men being men, began yanking their own chain (masturbating) and floors became filthy until the invention of the mop, when women took over the floor cleaning (except in all male households where the men have learned to share the mop).
So, yes, the hourglass shape is used to indicate sex and sexual charms.