All of these problems are just from assuming it will function in a very oddly specific way. Spawns don't have to be set job by job, other servers have no issue categorizing the player jobs into "setspawnrepublic" and the EJ jobs as "setspawncis", these are extremely specific issues that can easily be fixed just by coding the command in a certain way and I don't see why they should take away from the utility of the command overall. And as I've already said, they shouldn't be permenant, they probably even couldn't be permenant between map changes as different maps have different scales and having the same spawn between maps could result in people just spawning in the void, so I'm not sure why it would ever be coded that way.
Also you're *really* underestimating the utility that this would have, you're saying most maps default spawns are good as if GMs always just use a map the way it comes, which is far from the case, often times there is an obscene amount of building that can completely transform the layout of a map to where it is unrecognizable from its default state, just look at any of the flatgrass deployments there have been, you can't really just have a "pretty good" default spawn with how massively changeable map layouts can be. And this would eliminate a lot of unnecessary work as already stated earlier with the whole tac process which never goes smoothely and often has to be revisited mid event.