Here is what I know. The extended tube at the end of a filter can is usually there as a stop. The excluder, the little rubber thing that looks like a set of lips...sometimes referred to in my part of the world as a dust pussy, located on the bottom of the filter housing facing down is there to drop large parts of debris out of the air stream being sucked into the filter and water also. Large pieces parts can lodge in between the pleats of the filter and as the air is sucked into the engine vibrate in the low parts of the pleats and eventually vibrate a hole in the filter media. Once this little hole starts, it only gets bigger. You, or your mechanic will not see the damage for a very long time, especially if the filter minder is used, it will nor register because the hole in the filter is letting unfiltered air into the engine...it is the path of least resistance. As for the water, the liquid will make the media wet, imagine that! The wet media will rip under the strain of the CFM the engine requires resulting in the same scenario as above.
That 5 extra inches of metal stops water and large parts from getting into the filter media. The velocity of the air spinning into the housing forces water and large debris into that area of the filter and into the dust pussy/excluder area so at the pre trip and post trip you as the driver can squeeze the pussy and let the debris out.
My advice is to NOT remove it. But your stuff ain't mine, so I guess you can do what you want with ur stuff. Just be aware of the consequences.
IF the filter mfgr didn't want it there for a reason, they would have left it out. it costs them money to put it in and if it wasn't there, the mfgr would be on the hook for engine damage.
But what do I know?