I think it's mostly a handful of vocal people who got their cheeze-build nerfed. Skill builds also don't work in the same way anymore so anyone invested in a 8k+ build needs a completely new build. Sad, but that's the way of these kind of games. Metas come and go.
And it's funny that all these people complain about nerfs, but not about all the things that were buffed.
Overall we're better off. E.g. my turret did only 2k damage before the patch, and now (at GS 503) it's hitting for 7.5k which is not to be sniffed at with the fire rate it has. Same for seeker mines: 40k -> 140k damage.
Just keep in mind that there will be more balancing patches, and ones that go way beyond what was done this time. You will rebuild at least 5-6 times over the next coming year or two.
Full patch notes here:
https://forums.ubi.com/showthread.php/2032255-Patch-Notes-Invasion-Battle-for-D-C-April-5th-2019