The pay improving (or not) is a separate issue from the game itself. 9ball is fine and the direction it's gone is great. In order for there to be more money in the game, the solution is not endless tinkering with the game rules, it's about attracting a wider audience. That begins with making the game accessible to people of all ages.
Pool is fairly unique in that it's a game that many can't even access until they are 18+, or even 21+, since it's often found only in bars. Pool tables are a big investment in terms of money and space, so there are relatively few of those around in homes. Thus, very few kids grow up playing and loving the game. How popular would football or baseball or tennis be if people were effectively barred from playing it until they were 21?
More purely athletic sports (like the aforementioned) are popular with kids. More intellectually-focused games, or games that require fine motor control, are also popular--just look at video games. There's likely a large potential market for a game that straddles those lines, like pool. It just needs to be made accessible. Until pool is a readily available entertainment option for most kids, we're all just rearranging chairs on the titanic with all this tinkering.