Yes it actually does tell you to expect tension though and people that make this argument are being dishonest. One Piece is CAPABLE ot being goofy, just like its CAPABLE of being serious.
One of my favorite moments in One Piece is Luffy punching the celestial dragon. Reason being the fishmen subplot was introduced 400 chapters prior, and yet the discrimination of the fishmen was something that was finally revealed during an arc where the HIGHEST authority of the World Government (Celestial Dragons with Admirals) was at their peak. This caused EVERYONE else (Including Kid and Law) to look the other way during the mistreatment, oppression, captivity, and enslavement of creatures who were supposed to be be lesser then. Luffy then challenges the status quo by punching the Celestial dragon, and this is further explored through the pain the very same world government caused Boa Hancok and then Jinbei. Which then further lead to the serious overtones during the fishment island arc and ALL of that will eventually lead to the fishmen being liberated by Luffy on a large scale.
When Luffy finally liberates the Fishmen, should I expect a serious moment there? Or should I expect Bugs Bunny Looney Tunes?
If I should expect a serious moment, STOP acting like its silly to expect tension from One Piece. It balances between silliness and tension, and with an arc of this importance, people were expecting more tension and less goofy, and yet we got the opposite.