You're right, it's not balanced. I can see their reasoning for making it this way though. They probably figured that since chip damage obviously is not nearly as good as normal damage, then in order to make block pressure effective as a play style, they have to give it an added benefit to compensate, but that doesn't take into account a couple of things. For one, you gain a lot of meter while you're being hit, but the player hitting you does not, so characters who get most of their damage from normal damage and have no chip damage game are already at a disadvantage in that regard because their offensive game requires giving the opponent meter.
Second, normal damage has a definite end. You get combo'd, the combo ends. Now you have various methods of getting your turn started, especially after all that meter you gained from getting combo'd, but with run cancel pressure and stagger pressure you are in an indefinite state of losing with no way out without a correct guess, which if you guess wrong you take huge consequences. It's ridiculous that many times when you're losing a round to stagger pressure, it's actually a better idea to just let them hit you so you can gain some meter for the next round and stop serving meter to your opponent for free. It should never be a good idea to let yourself get hit in a fighting game ever; it makes no sense and proves how unbalanced block pressure is without a second thought.
They could fix this by making block breakers 1 bar so you have a guaranteed way out for a reasonable price, but because pressure characters gain so much meter, it will buff the pressure characters even more because they'll be able to block break every time you get on them. I think they could balance this though by giving slight meter gain to the person blocking. The amount of meter they gain should be exactly half of what the player on offense gains for attacking your block. So if a normal on block gains the offensive player 4% meter, then the person on defense should gain 2% meter. If they made this 1 small change on top of making block breakers 1 bar, this game would instantly become much more balanced, fair, and fun. Every S tier character in the game would immediately drop to A+ or even A tier except Summoner Quan Chi, but he just needs a mid hitting bat with more damage scaling and he'll be balanced regardless.
Aside from that, matches would last significantly longer, zoning would be used more often and become more effective, enhanced tools would become less of a constant threat since meter would be used for block breakers a lot instead, and 50/50s could be denied in some situations without having to guess. If NRS doesn't make these 2 simple changes it will be a huge disappointment. Even just adding a bit of meter gain on block by itself would be a big improvement.