I don't understand 3/4 length sleeves

[Technical]

Especially on jumpers/cardigans/jackets.

Surely if you need a jumper it's a cool day and you need long sleeves.

So many about though, I suppose it must be me. Drives me wild when I pick up the perfect jumper only to realise it's not perfect at all because the sleeves serve no useful purpose.

Why do you 'need' long sleeves if it's a cool day? Unless it's freezing 3/4 sleeves are fine.You can also layer them.

I never have a cold lower arm when wearing them

I thought that, but actually I push sleeves up constantly at work. So now I wear lovely smarty looking 3/4 sleeves. Perfect and a fine degree of warmth!