For sure big tanks are awesome. To try and bring the ocean into your house is so cool. LEDs make it possible to keep utility cost down.
Salt and fish feed seem to be the big cost. But to see the tangs grow and swim is neat.

At the same time, as big tanks are awesome, wife and I keep finding ourselves buying smaller tanks. Even pico tanks. You can put them anywhere.
And again LEDs with small footprints have opened the doors for small tanks.