And I fairly doubt that Soran was able to upgrade the BoP extensively.
Granted, he would be able to construct shielding for the trilithium torpedo so it doesn't burn up as it approaches the star ... then again, even with those enhancements to the BoP (provided they were done to begin with), the ship shouldn't have held out as long as it did in battle.
The latter may be true, but the former should be considered a factor here. Soran was years ahead the Federation in many things technical, and he had somehow convinced the Twisted Sisters that attacking the Enterprise
wouldn't be suicide - so why not take at face value the surprise that everybody experienced when Riker's first shot didn't end the fight?
The crew also acted in a very idiotic fashion. Geordi was held captive by the klingon sisters for some time and the crew knew of their deceitful tactics.
Why didn't they bother to check the visor if it's been tampered with?
But that assumes that the tampering would be detectable. Soran would see to it that it wasn't.
Also, rotating shield modulations very fast even with Geordi looking at them would likely not allow every shot to go through the shields.
We have no idea if that's technologically possible. It sounds quite plausible that shields just can't do that sort of thing: the constant retuning might either wreck the hardware, or then result in shields that are constantly out of whack and give little protection. And rotation has never worked too well as a defense against anybody, neither the Borg nor the Jem'Hadar, so it just makes sense that it wouldn't work here.
Again, as for the Galaxy class production being suspended ... I don't think it would happen.
But again, what suspension? DS9 shows more Galaxies
than the six the TNG Tech Man speaks about. And there's no real reason to think that the Sovereign
would literally succeed, let alone displace, the Galaxy
class. It's just another parallel design, only somewhat newer than most - perhaps an Excelsior
replacement at a long last, with many similar solutions?