From my perspective, I've worked a long time towards having the big three with engineered shields, and I don't want Frontier messing with them. The drawback of flying a big, expensive ship is that if it dies, you get a giant rebuy bill. They also tend to be easy to hit and less maneuverable than their smaller counterparts, so they need those shields to stay alive. So, they were much harder to hurt, but when they died it cost you more. They are easier to hit, but have a lot more hitpoints. That is balanced. But by all means, let's make them useless in open because a bunch of pvp-ers want their fights to be shorter.
If the shields get nerfed as proposed, why would anyone fly a corvette or a cutter in Open? Shields will go down much quicker now, and before someone says "but tougher hulls", hull tanking isn't that great in this game and players have loads of options to get around the fact you have lots of armor once your shields are down. This nerf will make the expensive, end game ships useless in open. So, why do this? 99% of PvP-ers play FDL's already. So they've been complaining their fights last too long, and naturally in comes FD, charging to help the only part of the community to pay attention to, without considering how this will impact everyone else. This whole idea of "we want small ships to be competitive too" has been taken to ridiculous extremes - a 10 million build is not supposed to be competitive with a 900 million one. If that's not the case, congratulations, you just eliminated the primary driver a lot of people have for playing this game - getting the bigger, badder, more expensive ships. Why bother?
Also, this game is starting to suffer from the "too much tinkering" syndrome. I'm getting really, really tired of having to re-engineer my entire fleet because FDev "rebalanced" (read: acted entirely reactionary to whining of a few people on the boards) things yet again. To the point where I can't even be bothered anymore. Heat is good, heat is bad, let's reroll. Incindiary good, incindiary nerfed. Corrosive very effective, corrosive less effective. Cascade rails pretty much mandatory in pvp, cascade rails not that great anymore unless used with hammers. And now, shield booster stacking, guess what, you engineered all of those boosters for nothing and your cutter's rebuy bill of 45 mil will now preclude you from taking it out in open ever again. This is not a good way to do business.