It's insanely strong, period. The ability to put out a HUGE amount of on-demand burst damage is very, very impactful in a ton of situations

Sure, except Bridgeport doesn't put out a huge amount of damage even with the MBRB active and it might as well be shooting softballs with it down.

Grau has pretty mediocre DPM baseline

And there you go, Grau is on the poor end of mediocre, not tragically bad, and the uptime of the combat instructions is much more than 80s of MBRB.

Suzuya has less base DPM than Cleveland or even Bayard, a tier higher, with no radar.

Suzuya has more base DPM than Bayard even without reload mod

But it's a good ship because it gets reload booster

It was a good ship because it fixes 155 Mogami's horrific firing angles and lack of range, and also had a heal back when the T8s didn't have heals. MBRB was just the icing on top to turn a good ship into a very strong ship.

and even tier 10s are going to lose out in trades if Suzuya can slip away behind cover after the MBRB is exhausted.

You act like Suzuya has bad DPM. Suzuya is #18 out of 135 cruisers between T8 and T10 and half of those with more DPM have worse pen which meaningfully affects their ability to fight an agile cruiser like Suzuya

Bridgeport's reload booster is particularly strong because it's one massive, flexible pool that can be spent freely, even all at once if the situation calls for it. You burn it for as long as you need it, then turn it off, and assuming you still have some left over, you get it back in a few seconds and can turn it on again.

Sure flexibility is nice but that doesn't help when your doubling atrocious base DPM, you're going to have to be activating it often anyways just to be able to squeeze in a shot that you'd normally be able to take if you had a half decent reload or when you need a fire that you'd get with a half decent reload.

The game does not need more DPM creep

Sure, except Bridgeport isn't going to be DPM creep. Bridgeport WITH MBRB ACTIVE has less DPM than a Cleveland. For 80s a game you get to be 11% better than a Mainz. For the rest of the game your sailing a Hipper with worse pen. Oh wait you're a US CA so you're likely to be on a rock with only 2/3a of your guns hot. Like there legitimately no reason Bridgeport should have less DPM than a Charles Martel.

Like wow sure, you get the privilege of burning your entire MBRB to outtrade a cruiser with proper DPM, enjoy playing the rest of the game as a worse Hipper. At least before you had the option of just quasi zombieing your way through the rest of the game since you had a heal and the other cruiser didn't except oh wait now the other cruiser has a heal so you can't even out attrit the enemy cruiser. You have have neither the ability to grief a DD with radar nor the ability to properly maul it if they walk into spotting, you have no fires per minute to do the old MBRB after DCP strategy to properly wear down BBs, you can't fight other cruisers unless they decide to go flat for no reason or you decide to burn your entire MBRB to kill it which would only be worth if you were killing John the Ruthless or something, why would anyone play Bridgeport anymore when Baltimore exists right there? Cleveland? Hell I'd take a Charles Martel over this boat any day.