I'd counterargue that with "what viewers can you hook into a wrestling show anyway?"
Here in the states, wrestling has become a punchline in the mainstream, so it's a truly niche "sport". There's really only 2 types of people who'll turn on Impact for the first time:
-People who hear about it from friends and watch it with them
-Older fans who've stopped watching who still could have some interest
...and who knows how many of the second group you can attract? Maybe there were a few bored dudes on a Thursday night over the years who sat by the TV watching Cops and saw the Impact Wrestling thing on the bottom and remembered Austin and Rock and the fun times they had as kids and decided to give it a shot, but that's all the random people they were drawing on Spike TV already.
Otherwise the current wrestling fans - many of won't give TNA a chance - are all they can appeal to, so this just means more people will be catching it on WatchWrestling instead of live on TV.