We should be able to place fish heads. They're cute. We should be able to display them. Tiki bar drinks should be edible. If not, the millions of coins that we get from fishing are pretty much useless. We need real furniture. We can sit, but we have to sit on blocks? A real chair would be nice.
For fish heads the command /morefish toggle allows to place them but it turns into a normal head sadly. You can also use item frames among with an invisible item frames resources pack to do the same. A golden coins update is planned at some point and tiki drinks are meme items. I love the furniture idea though.
The reason fish heads can't be placed is because players asked for them not to be placeable. There were also issues with players that would steal fish heads from others and place them down; making them lose the fish info. I like this idea and ashes is right, there will be an update for the tiki bar in the future. Currently, we are focusing on resetting and the upcoming holidays. So, you don't need a furniture mod to make furniture in Minecraft. I make vanilla furniture all the time for PF. Mods like this will not be added to PF because it is extremely laggy. This is also why we will never add custom armor stands.