While I agree with much of your post, I don't think that LCA have as much influence as you think.
They are far from the only auction house in the UK - there is also DNW, Baldwin & Spink to name but three - and they are not the only grader - there is also NGC & PCGS both of whom are expanding into the UK and Europe. Neither are they the only seller of coins, there are many others.
That means that we have a choice. We can choose to stay with 'raw' coins or we can choose to go with a grader (LCA, NGC or PCGS). We can choose to buy at LCA or at one of the other auction houses or dealers. And, in auction, a coin is only worth what a bidder is willing to pay. Up to us as collectors to determine what we think the coin is worth and bid accordingly.