Google participation can only benefit the travelling public
Presently all the GDS/GRS systems such as Sabre, Galiileo, Amadeus - who supply ticketing services to travel agents and the like - all have their own public-facing retail outlets such as Travelocity, etc.
Then you have the 'independent' Expedia (owner of TripAdvisor), Kayak, etc.
What the public doesn't realise is that these outfits are rated as consolidators (airlines aren't allowed to discount flights to the public so they resort to using wholesalers and consolidators) and selling these discounted seats results in substantially higher income.
They foist these odds and sods on an unsuspecting public when they build routing and fares.
Most Register Readers are well travelled people and they know their optimum routing for given destinations. My familiar routings include YYZ (Toronto) to Europe (avoiding Heathrow); YYZ to SGN (SaiGon).
As a test I routinely insert these into the usual search engines just to see how they 'optimise' your routing whilst dumping their discounted seats. Invariably the routing is through the US and then eastbound through some intriguing and imaginative routes and often using numerous carriers. Using numerous segments involves, usually, change of aircraft. Using different carriers puts the passenger at risk of being stranded by the late arrival of one carrier and the need to wait for a seat on the next carrier - and YOU picking up the cost of hotel/food during your wait.
Of course any trip involving the U.S.A. involves giving all your information to Homeland Security as well as having those thieving TSA security/baggage checking agents stealing your stuff. Now TSA gets to look at you stark naked!
The optimum routing is YYZ >> HKG (HongKong) >> SGN (Cathay) or YYZ >> TPE (TaiPei) >> SGN (Eva Air). Today's pricing on these routes - 1 year return - is CAD$2,300 and CAD$1,600 approximately, (Prices from my REAL PERSON travel agent).
You'll never get these prices from an automated search engine as it's not in their interest to offer them.
What Google is bringing to the table is transparency and this will reveal all the competition for what they are - on-line con artists. If your flight is a single segment each way, feel free to use these automated systems. If your journey involves several segments in each direction no one offers a better service for optimising routing/timing/pricing than a real live travel agent in your home town where the travel agents reputation is on the line.
Few people have better search capabilities than Google and their expertise will only benefit travellers but will also definitely impinge on others excessive profits.
There are many reasons not to use on-line res systems as opposed to the real, live, travel agent. The agent does the work, her/his expertise and ongoing knowledge adds benefits to the mix. They can play 'tricks' that on-line bookers won't do to optimise your flight or seat.
How many on-line systems offer access by e-mail and/t telephone? How many res systems will help you get another flight if you miss a connection? How many res systems will keep an eye on you as you follow your itinerary? How many res systems will remind you when your last day of validity is drawing near? How many res systems will tell you when a 'seasonal' price break/increase is coming due?
Smart people use Travel Agents and Google will only add to their performance and services offered to the public which might put a big dent is some peoples profits, but remember that is your money inflating their profits through conflict of interest and deliberate/dubious business methods.
Little wonder they were out there paying lobbyists and calling on their political friends to get this deal killed.
Another overlooked aspect of using on-line bookers is security of YOUR MONEY. Using a booking system outside your country of residence means that most Travel Agent Bonding (as in refunding your money in case of agency/airline failure) does not protect you. Just see how Expedia, etc. help you recover your money!
(I have no interest either in a travel agency or Google)