It always struck me as odd that such a cheap barracks provides such massive early game benefits.
You can't even stop enemies from building it right in the center of the field (and, therefore, claiming that area). If worker goes straight towards the center of the map, you won't make it in time to stop it from going up.
These forward bases then act as launching points for early game attacks. Mismanaged your dudes and lost some models? No problem! Just take 5 steps back and you're good-to-go!
Normally, when units are damaged in this game, they must spend time going back to base to heal up. Instead, since you essentially can have a base wherever you want with almost no investment. So instead of spending 30 seconds marching back to base to heal up, you spend, like, 5 seconds marching back to your barracks to heal up.
As such, the downtime experienced for early game units is almost non-existent. You can almost always stay on the attack. And with the large requisition income afforded to players, you almost never run out of money to reinforce any losses you may have suffered. Forward bases are a massive component in shaping this strict meta.
Additionally, they effectively reduce the size playable-size of the map. They create "no-go" zones for your opponent unless they commit to a huge attack to try and take it out (and that is precisely what we see in this meta). Combine this with power-core objectives taking up space, and you start to run out of room very quickly. There's almost nothing to do but attack in this (boring) back and forth slug fest between player's forward bases. Half the maps in this game are pitifully small and suffer even more from this meta.
Perhaps I wouldn't mind so much, but there's almost no counter play to this "strategy." You can't stop it from getting up, you aren't ahead in economy because barracks are dirt cheap (so you can't get a unit-advantage the same way you can if the opponent goes for an LP), attacking it is a very risky proposition, and even if you manage to take it out, there's another 1 coming up right behind it in no time.
Like, what is the point in ever taking a doctrine like Tip of the Spear or utilizing the reinforce mechanic of trukks or Falcon? Case-in-point of forward base reinforcement being far too potent compared to other available options for on field reinforcement.