This observation has been made many times, both specifically about PA and about other tier 4 items. I believe the fix is to add multiple super-duper dungeons, but that is a TON of work. The easy way was simply to add them to Reno and Warehouse lockers. So when you say, "spawning power armor and implants in a reno available to bluesuits wasn't a good implementation", people already know it wasn't the best, but at least it was something. We did see PA in TC. Not any more.
A Glance-Back Comparison
There was a time when support perks did not exist outside of the leveling system. Some dev(s) split out some perks into Support perks. The idea was they would be available via quests, but the quests were not added yet, so they simply made the support perks available via dialogue with NPCs. Too easy, but at least it allowed Support Perks to happen. Again we have an example of a good thing in this game, but where full implementation requires a TON of work, ie making new maps (like Klamath tanker and GR mutant cave). So a shortcut was used, and that's how it was with tier 4 items last season - they were available too readily, but at least they were available. Only 1 quest/dungeon was added for tier 4 items: the newest Special Encounter, the robot bunker. Additionally, an older SE was altered for this too: the little empty Gauss bunker.
What To Do?
That leads us to what its going to take to flesh this all out. The mapper and dialogue editor are tools available for download. Any of us can use them. There is far more work to do than any couple of developers can handle, so dig in! It's not as easy as donating money though - it's time-consuming work. Slowhand has done an amazing amount of work to document and explain how to do developer stuff. If you're interested, you should certainly check out his posts!
If we the players don't do this, then we should expect that in ten years we'll still have some degree of this same problem, even though surely some content will be added by then. My point is, if we don't build it, then let's not complain about it not being where we want it to be. Also i suggest tier 4 item availability last season was better than now.