I feel like One Piece is mostly unlikable because of all the WTF moments and the fact that people's noses turn into dual waterfalls when they cry. But I feel like it's those WTF moments that would make it so entertaining as an abridged series (if done by the right people of course) and it would be easy because the material pretty much writes itself.
The only other unlikable thing I can think of is there is very little character development other than when the characters first join the crew. After that they stay pretty much the same and all the story is about is throwing these people into conflict and scenarios.
And of course...
4KIDS! WHY YOU RUIN LIFE???