Xcode is…not very extensible IDE, I'll grant you that. The true impact of XcodeGhost is felt to this day :( I wish it was more extensible, and have myself done sketchy things to make it so, but I entirely agree with you that this is not a positive by any means.
If you are dealing with Xcode settings, move everything you can into xcconfigs, full stop. Just do it. It will save you countless merge conflicts, you'll be able to do mix and match and inheritance easily, and you'll actually understand what your build process is doing rather than it being a black box. I have no qualms blowing away targets and schemes now because I can just make them on demand and let Xcode autocreate the rest. I can "rebrand" an app in seconds and undo the changes in the same amount of time. Things which get used by other people always have ⌘B do the full build rather than some strange dance of "oh CocoaPods changed those settings so you should try to not set your development team on these targets and the dependency analysis is a little broken so…".
Debugger variables are…fine, I guess? I think the biggest issue I have with it is that it's placed in a not-so-great place, where it is generally to small to really see things. So usually I grab that information myself through a combination of p/po.
Xcode is still slick, IMO. Performance wise I haven't seen a huge change–it gets steadily bigger and slower and more complicated, but at about the rate that I update my computer. The people testing Xcode are clearly not using an Early 2015 MacBook Pro like I am, so I write off some of the features like Playgrounds or Previews or many simulators, but other than that I guess it's fine? I certainly value that it opens "immediately" rather than "initializing" (looking at you, Java-based IDEs…).
Where Xcode really shines is the things you touched upon: its integration with LLVM is first-class. It's certainly my preferred frontend to LLDB. The ability to flip on a bunch of diagnostics with one click has surely found many bugs, and the the built-in tooling for debugging memory graphs and view hierarchies is quite good–yes, it breaks sometimes, but it gives me useful results that I can't quickly get anywhere else nine times out of ten. Instruments is certainly unparalleled on macOS for external developers, and in comparison to tooling elsewhere it's a very solid offering.
Finally, of course, it's a nice native Mac app that plays well with all the other ones. That has to count for something :)
If you are dealing with Xcode settings, move everything you can into xcconfigs, full stop. Just do it. It will save you countless merge conflicts, you'll be able to do mix and match and inheritance easily, and you'll actually understand what your build process is doing rather than it being a black box. I have no qualms blowing away targets and schemes now because I can just make them on demand and let Xcode autocreate the rest. I can "rebrand" an app in seconds and undo the changes in the same amount of time. Things which get used by other people always have ⌘B do the full build rather than some strange dance of "oh CocoaPods changed those settings so you should try to not set your development team on these targets and the dependency analysis is a little broken so…".
Debugger variables are…fine, I guess? I think the biggest issue I have with it is that it's placed in a not-so-great place, where it is generally to small to really see things. So usually I grab that information myself through a combination of p/po.
Xcode is still slick, IMO. Performance wise I haven't seen a huge change–it gets steadily bigger and slower and more complicated, but at about the rate that I update my computer. The people testing Xcode are clearly not using an Early 2015 MacBook Pro like I am, so I write off some of the features like Playgrounds or Previews or many simulators, but other than that I guess it's fine? I certainly value that it opens "immediately" rather than "initializing" (looking at you, Java-based IDEs…).
Where Xcode really shines is the things you touched upon: its integration with LLVM is first-class. It's certainly my preferred frontend to LLDB. The ability to flip on a bunch of diagnostics with one click has surely found many bugs, and the the built-in tooling for debugging memory graphs and view hierarchies is quite good–yes, it breaks sometimes, but it gives me useful results that I can't quickly get anywhere else nine times out of ten. Instruments is certainly unparalleled on macOS for external developers, and in comparison to tooling elsewhere it's a very solid offering.
Finally, of course, it's a nice native Mac app that plays well with all the other ones. That has to count for something :)