The subs are out there, available for anyone who looks. Once you've let them know this, it's up to them whether they want to go download them.
I got into OP with the Viz manga. I'd heard it was a good series, so I ordered it to help fill up a Viz order (their base shipping/handling charge is really high, so I try to order as much at once as I can). I enjoyed it enough to order vol. 2 the next time I did a Viz order. When it came in, I got in the car and found a comic shop and picked up the next 4 volumes. I was hooked.
When I saw that Cartoon Network was going to show the series, I was intrigued. I don't like dubbed anime as a rule, and I'd heard the dub was bad, but I decided to give it a try. My poor TV was made sad that night, as I shouted at it in fury. I'd caught episode 1, and the first words I screamed were, "Why the hell did they give a 17 year old the voice of a 10 year old???"
I still can't sit through a full episode of the dub. Luffy's voice makes me cringe. The changes are jarring. It's too painful to see.
Anyway, I decided to try the internet, see if maybe I could find fansubs. I wasn't holding out much hope, since it was licensed, but I felt compelled to try and erase the horrible memories that the dub had carved into my brain. It took very little time to find the subs, a few days to figure out how bittorrent worked, a few more days to get my WMP to play them (I'm not very computer savvy or patient), and now I am a happy OP addict.
The scars are still there, though. That damn rap theme gets stuck in my head sometimes…. (jabs fork in ears....)
My suggestion is, let people know what they're missing, let them know the sub is out there, and leave it at that.