I don't use it but I like that it is there. Old or not -- tons still use it.
The lady in the cubicle next to me at work has the IP7, she has to charge it every day because she forgets to at night. She used to sit with the phone plugged in with youtube videos going all day but not now, she can't, she has to stop listening to stuff while she charges. Seems stupid to me.
I like having the headphone jack, I actually find wireless ones very annoying. yes the sound quality is better but it hurts my ears and you have all the hassle of connecting it to bluetooth and making sure it's charged etc. I have dre beats and I haven't used them for a year because it's been more of a hindrance to me. I'd be very disappointed if Samsung were to ever remove this.