Why do earphones need foam pads?

Because if you're wearing them for extended times, then foamy ones won't hurt your ears but harder ones will. But if you can handle ones without foam totally well, then I guess good for you.

Foam pads are for your comfort, as some earphones might have imperfections along the bonding line(plastic). Anyway, if your earphones are comfy, then don't worry about the foam pads.

foam ones make them comfy... i lost the pads from my phone headphones and they really hurt to wear after that. i would recommend spending 2 dollars on a pair

Comfort

creates a pressured space for the sound to flow through, just makes it more comfortable and slightly helps the quality of the sound

It helps your ears

My science teacher says the ones without the foam ruin your eardrums more than ones with foam.It funnels the sound.

And it comforts your ears.

the foam pads are just provided to make the headphones "more comfortable" to wear

They're just for comfort, and to make sure no junk gets into the holes.

Just use your finger to put them on. If that doesn't work, ask a female friend or child you know to put them on since they have smaller fingers and are probably more tech-savvy.

To keep the working parts clean of your gunk.