Well, if we look back to the end of September and early October the community hated many of the original Mayhem modifiers and how they behaved. So Gearbox who clearly weren’t prepared had to make a new Mayhem level. Once we got Mayhem 4 we became accustomed to it extremely quickly. It took most people a few weeks at most to adjust. They probably tried to keep us busy and therefore started working on Mayhem 2.0
In concept nothing about it is really bad: It’s more challenging, more creative than just lowered/increased multipliers, gives better loot and we can adjust it to our liking on the fly. The problem is that they seem to fall behind on their content schedule, which lead to DLC 2 and the Mayhem 2.0 patch coming out with bugs. DLC2 had and still has many bugs, but they’re very minor, except for the gear without lootsource (which they fixed). Still overall, DLC2 was pretty good in terms of polish. But now it seems that time might become an issue more and more (this is purely my speculation, but it would explain a lot of the problems we experience right now). And now they can’t even get their hotfixes to do what they’re supposed to: Apply little fixes.
Ad to that the internal communication, which is an issue as departments don’t seem to talk to each other enough. At least that’s what I assume because otherwise I cannot really explain how they could forget to have some of the most important parts of the game not scale with the rest of the gear. Action skills, pets, grenades, shields and even chests not scaling with the Mayhem Level? Those are issues of a magnitude that I just cannot see how that didn’t get noticed without the lack of communication. It could have been that there were some devs that should have coded those parts into the package that would become the Mayhem 2.0 patch, but poor communication lead to them not getting the orders. Also, thinking about it: The amount of chests Gearbox has to go through to apply those modifications is immense and depending on how that works in practice, they might have to go through all chests in the game and assign a Mayhem Modifier to each separately. That’s a shitton of work to do. So it might have been as simple as a slipup from someone in a leading position just not thinking about it and therefore forgetting to have someone working on it. Depending on the structure of a company the mistake or oversight of one person can spell doom to a project or in this case, destroy the solid foundation they worked on for over half a year.
Long story short: I think that some higher-up just didn’t think about the changes that had to be made in consequence to the increases in stats in Mayhem 2.0 and the changes to how items scale. Someone might just not have seen the bigger picture and what had to be done to implement Mayhem 2.0 accordingly.