I'm from Maui and I go holo holo to Moloka'i on a regular basis. From what I've learned from my friends over there, CBLAISD's points above are spot-on. There definitely is some strong anti-developer sentiment on Moloka'i, but it doesn't directly translate into anti-tourist sentiment as long as YOUR attitude is properly adjusted.
The majority of Moloka'ians have made a decision, as a group, that they will willingly give up a degree of economic prosperity in return for not becoming "another Maui". They are horrified by things like:
1. Maui Upcountry residents who no longer have unfettered use of their own roads and emergency services due to the ubiquitous lawlessness, trespassing, and "screw-everyone" attitude of the universally-hated downhill bike tour companies.
2. Zillionaires who buy $5 million condos in Wailea which they use two weeks a year, who then spend 90% of the time between when they step off their chartered Gulfstreams to when they fly back out screaming at the local plumber "what do you mean you can't fix my toilet for five weeks????" or screaming at the local mechanic "what do you mean it'll take six weeks to get a new headlight for my Mercedes ????"
3. Local surfers and boaters who are losing unfettered access to their local spots due to abuse by unregulated, poorly regulated, or just plain uncooperative commercial kayak / surf / diving businesses.
Anybody who shows up on Moloka'i exhibiting anything remotely along those lines will have a hard time.
Read CBLAISD's post carefully, and you will have a magnificent time on Moloka'i. It's the last great "secret spot" in the Hawai'ian Islands, so shhhhhhhhhhhh - don't tell anyone.