Market prices are published in local time for an exchange. Customers might operate their systems at another exchange in another time zone, but there are no exchanges and no customers (actually departments of subsidiaries of a bank) publishing nor consuming prices on a UTC timescale. To store price data in UTC would only mean having to convert it back again before it can go anywhere and there is a real danger of losing the correct exchange timestamp during the varying difference periods I mentioned. Your ideas might seem harmonious from a technical point of view but your reluctance to face accepted investment banking standards and customer requirements wouldn't bode well for you in this environment.