However, I think that, perhaps, what will happen instead is that a new version of the UMC will be provided with a fixed NEMA 14-15 male plug and, perhaps, a slightly more sturdy construction. Then the interchangable plug UMC would be an optional product. A HPWC would mean large installation charges for many people. But, again, your point is taken and I concur that if people who use their UMC as their every day charger then there should be a more reliable/safer version available for that purpose and keep the current version (perhaps with improved connection lock) strictly for occasional use when traveling.
Your idea may be under Tesla's consideration: I stopped by my local SC to pick up a 14-50 adapter and was informed by the parts guy that all of their 14-50 adapter inventory had been sent back to HQ at HQ's request. He also stated Tesla is always improving parts and this was why the inventory was sent back. If you check out Tesla's online store the 14-50 adapter is now listed as "Out of stock". An improved version of the adapter is in the works.