You've been given examples of HSTs to the west. HSTs to and from Maidenhead (to say nothing of getting a seat in 1st Class on a peak time Turbo) and I'll add to that the 1915 to Swansea. Not one spare 1st Class seat on two occasions in April, as I noted when boarding at Reading, with numerous people standing.
I fully appreciate the greater good blah, blah, blah, that means capacity has been increased overall, and I applaud FGW for doing what they can with the stock they have, but that doesn't change the fact that on certain HST services some First Class passengers are now standing, whereas prior to the changes they weren't.
Castigating folk for not being proactive in making seat reservations (Season or Anytime are flexible tickets - perhaps they should block book reservations to maintain flexibility, thus making the situation worse) is just crass. These passengers have not brought the situation on themselves.
And don't ask me to offer a solution. I merely observe.
The only obvious solution to your observations would appear to be to reverse the change in seating layout. But, as I am sure your observations also tell you, the overwhelming majority of FGW services do not need acres of first class seats, as not enough people are buying first class tickets these days, whereas the number in standard is still rising in line with the trends across the industry.
What examples of HSTs to the West? You mean a vague reference to "the summer"? Such services have been busy in "the summer" since time immemorial.
HSTs did not even call at Maidenhead or Twyford until FGW put them on in recent years to help ease pressure, as Turbos could no longer cope on their own. But you appear to think this is just not good enough and they should also be providing oceans of first class seats for 18-minute-long journeys a few times a day made by people who, in many cases, bought a first class ticket to try to avoid the overcrowding in standard, and will happily go back in a couple of years' time once all the extra capacity arrives in the shape of electric services. And in the afternoon, at least, FGW is doing what it can to ease pressure on the 17.49 - and the 17.18 Adelante to Oxford, which is full and standing well past Reading.
Don't bring the 19.15 to Swansea into this - that's a different kettle of fish, due to various factors unrelated to the number of seats provided in first class, and one only ever likely to be solved by providing another HST as a relief five minutes later - but there isn't one available and it would appear that one that is coming free from September after the overhauls is already slated to help out your friends from Maidenhead...
I know what a flexible ticket is, thanks. But as observed previously, no matter what the price tag, it does not guarantee a seat, just a journey from A to B.
And if you were travelling between London and the West Country in "the summer" would you do so without reserving? I don't believe someone needs that much knowledge of the railways to work out that a reservation might be a good idea at that time of the year, or Friday evenings, Christmas and bank holidays...
And are you really suggesting that a train manager would make people stand if a train had left London with empty seats where someone had clearly not taken up a reservation?