I'm relatively new to aquarium keeping but here's my 2 cents.
Any animal we keep should be comfortable, stimulated, and kept in clean conditions. Agreed nothing we can make will ever compare to their natural environment but we should try as much as possible to make them feel safe. i.e. give them cover.
Using the lowers aggression card doesn't wash with me I'm afraid. You must ask why any animal gets aggressive in the first place, In the case of territorial or non schooling fish, their natural behaviour is to aggress intruders in their area, we have personal space and when other people intrude on it we get aggressive, IMO an animals personal space can only be shrunk to a certain point before things go wrong, if you have aggression problems solve it by giving clearer territorial markers/ rearrange tank etc if that fails give them more space by selling some off or a bigger tank if you cant bear to part with them.
I have a friend who is still distraught about the fact that his Oscar was killed by its tank mate Flowerhorn, but the truth is he had them too confined you can blame the fish all day long but in reality if we choose to play GOD then we must take responsibility.
Rant Ends