I see taxes in case of securities trading is just form of insurance, and attempt to regulate and stabilize the price by encouraging holding long term and easing on stupid people getting broke, by deducting losses from the taxes, giving back money basically.
From one side it should look positive for the market, theoretically prevent pump and dump schemes, reduce volatility, maybe give more confidence to institutions and encourage adoption.
On the other side, for the average person it's annoying because it's more hassle to do, it discourage smarter decision making, not everyone is honest and wanna care about it, the government takes their cut as well, but it is what it is.
I wouldn't complain if the system was fair and automatic, so you don't need to run around doing paper work, hire accountants and lawyers, and hope everyone else doing the same. So we'll see what happens.