You show the crowd to:They drew 2,000-2,200 for these Mexico tapings and theres pictures from people who went on twitter showing they sold out these tapings with over 2,000 people in the arena. Again the lighting is darkened because they want the focus on the performers not the crowd.
Impact Wrestling attendance is 2,000-3,000. So their crowds aren't small its just that they're going with the old school approach where you want the focus to be in the ring and not the crowd like how the NWA and AWA ect did back in the 70s and 80s.
1) Heighten the excitement
2) Show off that you are drawing
Impact drew 2K - 3K fans? They should have lit that arena up and shown it off! That's a nice launch point to illustrate that the promotion's darkest days are behind them and that it is on the way back. Instead, they could have drawn 30,000 fans and it would have looked no different than when they appeared at Sam's Town Live.
While I get what you say, I never understood the advantage of "focusing on the ring". It's Bill Watts WCW stone age production values, and by that logic you could have a sold out WrestleMania in Dallas that you never know is sold out because the lights are off. At that point, why have it at a stadium at all? Why not just the Liberty High School again, as it was for RAW in 1995? You'd save a ton on production costs.
To me, a blackened arena speaks two things:
1) You're ashamed at how small the building is, so you don't show the crowd
2) You didn't sell out your venue, so you're trying to hide it (ala the WCW Clash of Champion at the Super Dome, or the 1988 Survivor Series in Richmond that was only half filled)
Furthermore, you couple that with the trend in the last decade in NXT, ROH, and Impact where you have relatively interchangeable male wrestlers who are bald or have short black hair, wrestling in black trunks, wrestling in a ring with a black apron, competing on a black ring mat (at least Impact's is lighter), in a ring surrounded by black guard rails or crash pads around the ring, with black mats outside the ring, and in a building where the lights are turned off and everything around the wrestlers is black. It doesn't appeal visually to a new viewer at all. Impact should be trying to regrow its audience with current wrestling fans and the occasional casual viewer. That sort of stuff doesn't make you want to watch at all. It's Soviet brutalism as a production value, grim and bleak.