you have some firms that know how to quote a product and can make enough money doing it to be worthwhile. They've done a lot of research and implemented systems

you have some firms that know how to quote a product and can make enough money doing it to be worthwhile. They've done a lot of research and implemented systems to do that. Change the rules on them for arbitrary reasons, the firms that were there leave. At least long enough to build new systems and trading strategies. Who replaces them, anyone? Why? Increase the tick size, liquidity drops. Decrease the tick size, liquidity drops. The moral there is know why you are changing the rules in the market, how you are doing it and the implementation details and side effects that will result in getting the result you want or just don't do it. This could be better is garbage, know it is. Change is not good for its own sake if you want people to quote.