Then won't you get mostly the same thing, at a higher spread? Market makers would be hurt less by that than the investing public... in fact exchanges give fee rebates to market makers precisely to help liquidity.
This is hardly a new idea, and it is clear the system needs to be improved. From Wikipedia:
“Keynes was among the first proponents of a securities transaction tax. In 1936 he proposed that a small tax should be levied on dealings on Wall Street, in the United States, where he argued that excessive speculation by uninformed financial traders increased volatility. For Keynes, the key issue was the proportion of 'speculators' in the market, and his concern that, if left unchecked, these types of players would become too dominant” http://en.wikipedia.org/wiki/Financial_transaction_tax#Secur...
Not to mention massive compliance overheads and loss of efficiency in the middle office. Such a tax could in theory only be implemented on lit exchanges! More volume would move to the dark ATS'S/ECN's and Crossing networks. Shit people would just internalize and cross order flows and never actually execute a "trade". Making your solution pointless.
Keynes hahahahaha.
A large part of his failure is assuming his so called "dominant financial speculators" and the government overall or at least the financial regulators would not simply merge, which they've done. Therefore even if his tax was a good idea instead of an inherently dumb one, rather than being implemented correctly it would just be another crony capitalism weapon probably wielded exclusively as a club to pound down the "wrong" people, it would hardly be used to control the dominant financial speculators because they're the guys who purchased the elected officials to begin with!
You could argue that High frequency traders and other hedge funds might be a problem for the market but to lump the market makers in with the high frequency or even prop shop funds i think is being a little harsh to them.
What don't you like about the lowly market makers? Hell the Canadian option market would be a lonely place without them:)