I'm sure this won't be a popular opinion as this forum is populated with passengers who fly in the planes rather than investors, but BA and IAG as a whole are the most economically viable non-LCC airline group in Europe, which is largely due to the cost-cutting and restructuring at BA and Iberia that happened under Willie Walsh. AF-KLM is a perennial basket-case despite KLM being a very profitable airline and Lufthansa group is somewhere in between in terms of profitability while offering a similarly uncompetitive J product in the flagship airline. Similarly in the US, I don't think anyone is really praising the product offering of any of the US3 (or Air Canada for that matter), but they're now more profitable and viable businesses than ever. Just about every airline that people enjoy flying because they offer a great product (and particularly a great premium product) is either heavily state-supported or unprofitable and close to in bankruptcy (of course there's also plenty of state-supported and / or bankrupt carriers that are not great to fly either, but that's neither here nor there). The airlines that are viable, private, "premium" / network airlines, very few people would praise for their "great" passenger experience.

The viewpoint that there are negative returns to an airline for a better product is further reinforced if you look at the return on assets (which is a critical metric for an asset-heavy business like airlines) of various carriers. The carrier with the best RoA across Europe in 2019 (the last pre-COVID year) is...Ryanair (and there's absolutely no one praising their in-flight product) at 6.9%. The lowest LCC / ULCC in Europe is Wizz Air at 4.0%, and Easyjet is 4.6%. Across the 3, the average is 5.2%. Compare that against IAG (5.4%), Lufthansa (3.0%), and AF-KLM (1.0%), which together average 3.1% despite each of the legacy groups having LCC arms that are likely bringing their average up. Looked at differently, Lufthansa and AF-KLM have worse RoAs than any European LCC / ULCC, while IAG is doing better than any other airline group other than Ryanair.

Similarly, in the US, the LCC / ULCCs average 6.4%, with Southwest at 8.8%, Alaska at 6.4%, Spirit at 5.5% and Jetblue at 5.0%. The legacy carriers average 5.4%, with Delta at 7.4%, United at 5.9% and American at 2.8%. Interestingly, the US legacy carriers are mostly performing poorly because of American, with Delta having the second highest RoA of any carrier in the US after Southwest and United coming in right between the better 2 and the worse 2 LCCs / ULCCs. Nonetheless, the trend of carriers that offer less and lesser premium products performing better financially is pretty clear in the US as well.

Also, across the board, note the general trend of reduction (in both number of seats or number of routes) / outright elimination of long-haul first class. Some aviation bloggers will tell you there's a market opportunity in offering an even better first class product (mostly because they want to fly it on a saver award redemption), but just about every company that is actually in the business of selling that product is looking to downsize or eliminate the offering. Even in the state-owned carriers, Emirates went from 8 F seats to 6 in their new 777 product, Singapore similarly went 8 to 6 on the new A380 suites, and Etihad and Qatar are out entirely (though Qatar will maybe introduce a new one for 2-3 high-yield European routes).

Offering more premium offerings is of course great for passengers, but not great enough that enough passengers or their corporate expense accounts are willing to pay for them at a high enough price to make them viable, and in a business as competitive as commercial aviation, the airlines that want to be viable businesses respond according.