Hi @MyNameIsNobody, I have worked as an A&P (and IA, mostly on large turbine stuff) in the past and am currently a Mooney owner, so I hope I can try to give balanced consideration to both sides of the issue. I think, your last comments capture the core tension here:
1) "OEM PMA light build IS available"
Core issue being: legacy certified tech is available and sometimes cheaper than new Tech non PMA, often much more expensive, but it IS available...
... but in this case it is it is incandescent and **generally** deemed a technology that is a) less bright, b) less reliable and c) draws more current than a non PMA LED which would, in most cases, be considered be "safer" at least to the extent that it matters at all that lights are on aircraft (LED's are more likely to be seen, more likely to be left on during times like daylight when non-LED are pretty much invisible) ....BUT...
2) "a $200 bulb is ridiculous"
Core issue being: Funds are ultimately limited to all of us and we have to make compromise choices: Upgrade, Keep, Do Without. (unless you print the stuff), money spent on "X" no longer exists to buy "Y" and that the opportunity cost. So, even those who may not deem the $200 bulb "ridiculous" may have had to use those funds on other stuff that are more fundamental (than lights) to safe/legal flight. Consider what we can do for aircraft safety/compliance by way of maintenance with the difference in a certified pair of LED landing lights and a non-certified LED set.
Resulting gotcha: Some new technologies are so "new" that they are totally unknown qualities and would be sketchy to install in any aircraft if they were a critical system. Some "new" technologies are highly vetted so their performance/reliability are well established vs older technology (e.g. LED's vs incandescent bulbs). But the bigger issue is that the technology world is accelerating far faster than a governmental certification bureaucracy can keep up... and that rate of innovation itself is accelerating further so the gap will continue to widen. The tension really comes to a head when the process which was originally intended to certify parts to make sure that safe parts are in airplanes, in more extreme cases, can get so far out of pace with technology that the net effect of the certification process piles up 1) time delay to certification, 2) large certification-driven expense to the few "approved" parts that make it to market and 3) a dynamic of warding off technology providers who blow off making products for highly regulated environments in favor of less regulated markets. So, ... in more extreme cases the certification process can, in the net, achieve exactly the opposite effect of its core intent/mission/rational for existing. Further complicating that in the Mooney case is the grey areas in the FAR/AC and IPC for the aircraft (apparently) proscribing the light housing but not the bulb. In cases like these LED's as with so many things, now there is no opt out of risk, just choices of risk flavor for both the pilots (balance personal vs financial vs legal risk) and for the A&P/IA's to balance the likelihood/severity of real legal risk (favoring a conservative interpretation of the rules) vs. allowing certain things that they deem safe and within the rules (more liberal interpretation).
One of my A&P instructors back in 1988 use to answer "You pays yer money and you makes yer choices..." to a lot of questions that students would ask... It frustrated people often, but I think he was helping prepare them for the the big, wild "out there".
Just a thought (or two)