It's true to some extent. The personality of angels varies from fish to fish. Some pairs are fairly docile, some are murdurously aggressive. It sounds to me like you want to enjoy a decorated tank with more than a pair, while leaving your options open for breeding a few fish. There are a few things you can do.
Arrange decorations in the center of the tank to create a sort of natural divider. If a couple pair off, they will probably find an area at one side or the other of the divider. The divider breaks the line of sight. Have a divider ready just in case, and have an area set up that it will fit into. If the aggression gets too far out of hand, you can add the divider to give the non-aggressive fish a break.
Have taler plants towards the back corners. This gives them a better place to spawn, while taking them further away from the main area of the tank. They will feel as if they have more territory.
Pull out the eggs after they spawn. If there is no spawn to defend, they will be less aggressive.
Sometimes switching pairs or individual fish is the only option that really works. This involves multiple tanks, pairs, and time.