It is not unreasonable for people to not want to replace their old fixtures, which they like and chose at least partly for aesthetic reasons with new ones just because the technology has changed.
If you have designer fixtures or antiques I can understand and you should preferably continue using the original conventional bulbs since that is where they were designed for.
I must not think of the idea of a led bulb in an original Tiffanies.
But for the rest it is silly esp when you see how easily people buy and throw away their other electronic devices some costing many times more than all the fixtures in the house.
So I claim it is mostly not esthetics, it is lazyness for upgrading esp. when it needs extra work because it does not fit, which is ok but should be named as such.
Also, it's not like the LED folks are warning everyone that the bulbs that fit in many old fixtures will basically fail much sooner than an ordinary incandescent.
Because it depends on the fixture. If it has enough room or openings to keep the airflow keeping the bulb relative cool there is no problem. However many fixtures are closed at the fitting, and if upside down there is where the heat will be kept, ergo short lifetime. There are gazillions of different fixtures go try to explain to mrs Jones age 75 which fixtures are ok to upgrade and which not.
But you can hardly blame people for not wanting to replace a fixture with a new one that is essentially non-repairable and with no replaceable parts, especially given the failure rates reported in this thread and others.
If you are over 45 and use the dedicated led fixture for 8 hours a day and turn it down to 75% it will outlive you , perhaps the driver capacitor should be replaced sometime

Personally, I have not replaced the fixtures in the bedrooms in my house because they are absurdly large and unless I want to get similarly large replacements, I would have to respackle and repaint around the fixture for it to look nice, a job I don't usually feel like doing.
I mentioned that above, but if it is much work I understand, if it is part of the architecture or you like the esthetic looks I also understand. The price might be to have to replace the bulbs sooner than expected due to lifetime issues.