Which one do you mean?
* Pulse Audio? * Systemd? * Unity/Gnome 3/KDE 4? * Windows 8/10?
It's not that people hate something that's mainstream. The problem is that mainstream is often a polished turd which companies or alternatively gifted individuals try to sell you as something which is better and novel, while being in an order of magnitude less usable and having tons of bugs.
I think this is exactly the kind of comment that Shuttleworth was talking about.
Let me put it this way: if this software is such an obvious 'polished turd', why haven't *you* coded up a replacement? If it's that easy to enumerate the things they did wrong, why isn't it easy for you to just do it the right way without bugs? (Please don't take this personally, I'm using the universal 'you' for all people reading this)
PulseAudio is not perfect, but it is improving, and is itself a big improvement on older sounds systems that often didn't work at all for many setups. Systemd is not perfect but it is a huge improvement on the old script init that couldn't handle modern features like hotplugging devices and sleep mode. The desktops are not perfect but are trying different design philosophies out, because honestly, user design is not a 100% solved known problem, but the latest GNOME 3 and KDE/Plasma 5 releases are very nice and polished (your comment including KDE4 suggests you haven't tried KDE in a while; I encourage you to do so). Were those things buggy at first? Sure. But I suspect many distros rushed (possibly a bit too fast) to switch to them precisely because the older systems were not working, and they were ready to get them fixed. Even Windows 8/10 have parts that I dislike (mostly the telemetry, and 8's inconsistent mix of metro with the old GUI) but they deserve kudos for massively improving their default security posture and modularizing the system (I have way less crashes than XP/7!).
The answer is that modern software engineering is a VERY hard problem. And like many things in computer science, there are lots of trade-offs -- you often must sacrifice one thing to win at another. Many of the issues people complain about are design decisions that are not necessarily the result of bad programming practice, but rather the trade-off, and the developers are showing they might have a different priority than you. And that's ok. No one has to agree 100% of the time on anything. But that said, you can respect someone's work and decisions while still holding your own differing opinion, and that often gets lost in the arguments. Shuttleworth had a not-invented-here problem on some issues, but the community's response was sometimes just as bad. Both sides had merit to their arguments, and both sides have made mistakes. It happens. Let's not demonize anyone for trying to see their vision through.
I'm in no way condoning laziness of course -- I expect all projects and developers to quickly address security issues and release but and security patches promptly, for example. The privacy issues that Ubuntu and especially Windows brought up are worth a very critical eye. But let's remember that software is hard for anyone, no matter how much experience you have, and stop tearing each other down. In fact, in true open source spirit, contribute bug fixes