First off, CM10.1 is not a mess and it at least as reliable as any stock ROM without bloat or stutter. You should give it a try.
Secondly, you give up far more than that. You don't even have support for IMAP IDLE (push) on WP8 - something that was available on the very first, pre-Treo PalmOS phones. Hell, you only have ONE choice for an email app. You give up user-replaceable batteries, SD cards for expanded storage, file system access for manipulating files:
- don't have a .rar, .gzip, etc. app on Android, webOS, BB10 or MeeGo? Just open a terminal and open it that way.
- want to make a backup copy of a file, store it in a locked directory and then work on the copy? No problem on those other OSes.
- want to connect your phone to your laptop on a plane and pull email attachments that you received on your phone onto your laptop? Not on WP8.
- want to transfer that PPT that you spent the entire flight to Germany preparing to your mobile before you land so you can send it as soon as you can power up that phone? Not on WP8.
Competition and innovation are good. Innovation is best when the innovators succeed. Apply may or may not be dying, but the paradigm of the iPhone changed everything. There would be no WP8 as it is today without the iPhone. webOS was better and lost the fight and many of its innovations are lost (at least for now).
What is the innovation of WP8? Tiles? Sorry, that was already patented. Nice animations? Seriously.
As for the use cases above , they don't really do anything for me. Production work would get done on a tablet at the very least , most likely a laptop or laptop/hybrid like my surface.
Like I said , for myself and others perhaps the large majority of the market , we want phones that just work and let us get online. That is why people like the iphone and the vast majority don't root their android devices.
Mize. It is great that you find a custom firmware to work well for you. However for me and i'm sure a lot of people that is not a way to go. IF I mod my phone and then need support the carriers will laugh at me and send me on my way.