It seems to only break apps.
* Notifications
* Air Drop
* Face Time
* Native Full Screen apps
* Multi-touch gestures (mostly use with multi-desktop and fullscreen apps)
* Mac App Store (I like it better for OS updates)
* Recovery Partition
* App Resume
* Terminal improvements (I stopped using iTerm)
* Air Play mirroring
* Notes (and syncing with phone)
* Compressed memory
* Full Disk encryption
* Improved multi-monitor support
* Spotlight improvements
* updating while asleep
* hi dpi monitor support- Notifications : Had Growl, nothing new.
- Air drop : Perhaps but personally in no need.
- Native fullscreen : This is crazy. I turn iTunes fullscreen on secondary display and somehow it blacks out the primary screen for no good reason. Never using this feature.
- Multi touch gesture : Customizability is a joke. BetterTouchTools is what is keeping my sanity by applying custom trackpad gestures.
- Mac app store : Apparently this is big.
- Recovery partition : One of the great invention was network recovery but not like I use it often at all.
- Terminal : It was ok back then. Perhaps better if you say so. I do use SSH all the time. Never needed third party terminal.
- Air play mirroring : Don't have experience.
- Notes : Calendars, notes, reminders, stickies... What's coming next for note taking app? It's just cluttering my app folder.
- Compressed memory : Sorry I don't know what this is. Does this help you daily?
- Full disk encryption : Important feature.
- Multi monitor support : It was fine back then. As said above, part of it is a joke now.
- Spotlight : Maybe. I keep my files and mails all tidy, so I don't need a search helper.
I mean, Leopard brought Time Machine, grid view folder display from dock, quick look just to remember from top of my head which are all vastly useful and Snow leopard perfected it by making it lighter than previous OS. And today they boast they added like 100 new stuff which almost doesn't matter and I doubt things ever get lighter than previous OS these days.
Ever since they thought merging iOS feature into OSX was a good idea, it keeps adding useless pieces and they call it the best release ever.
Back then I thought Windows had tons of crapware on newly bought machine but funnily lately OSX is almost a victim of that from the vendor itself...
I love using OSX because of high quality third party apps. And in my opinion frankly Windows is still far worse.
And for OSX naming... I thought Apple is an international company. Tiger, Leopard etc was easy to read and understand as a word for us foreigners and now what? El capitan? I must think their vision is just getting narrower naming a OS to some local name they thought was cool.
It's not just foreigners. Even us on the opposite side of the United States have no idea what El Capitan or Maverick is or means.
a few sporadic replies:
* Notifications: very few things apps supported growl and I like the integrated implementation better. Growl also started charging money, which is fine, but yet another thing to juggle licensing and that friction drove me away.
* multi-monitor: People complained about multi-monitor handling in OSX /a lot/ until the last few years. I haven't heard of any problems recently (maybe I've missed it). I don't deal with it that much, but I still have problems with Windows and Linux...dialog boxes popping up straddling two windows, for example.
* Native fullscreen: Fullscreen API was added in 10.7, then changed in 10.8 and again in 10.9. It sounds like because of a limitation at the time of the initial implementation it was integrated with Spaces which blanked out the second monitor. If I remember, there was an option to have each screen use separate "Spaces" to avoid this and in recent version it works out of the box. I think some apps like VLC or iTerm still use their own fullscreen implementation--but now all apps can be fullscreened without developer intervention. I just pointed it out because as it exists today, it's a new feature like to use.
* Compressed memory: compresses RAM when it can. Improves performance on lower-end hardware. I don't know about this specifically, but I've seen this kind of thing actually increase performance where i/o is more of a bottleneck than compressing.
* Spotlight: I rarely use it for file search (that in itself hasn't changed since SL), but I use it all the time as an app launcher and calculator.
The reason your new applications require new versions of the OS is because the frameworks got better. If new versions of the OS were just adding new applications you don't use, then people would still write their applications with the older, better APIs.
At least in El capitan, I can no longer even touch any of system files even with root privilege. And then I could put shortcuts of the only apps I use in a separate folder but they add arrow badge at the bottom corner for each icons which is visually annoying, and I try to find out how to remove it, searching reveals I could rename the image file for that arrow but turns out I can't touch system files. No, I don't want to turn off that security feature just for this.
Next iOS feature that needs merged into macOS is, hide first party apps.