Apple has decided that their simplistic art-school level of design is more important than the human interface guidelines that made the Mac the success it once was. iOS rules the roost, and the Macintosh is a far less profitable adjunct to the iOS part of their business. Apple is saying it is better to make Macs dumbed down so that iOS users might buy them, than to let them be the capable and elegant machines they once were, and keep the faithful who stuck with the Mac through all the dark days of System 7 - OS X10.3, when we who bought Macs kept a struggling company alive. (I even bought Newtons and eMates, printers and cameras from them to help as best I could!)
Favicons are gone and it is deliberate. Glims no longer works with Safari 8 and may not be updated, so you can't add them to tabs that way. Your only hope is to bombard this page:
http://www.apple.com/feedback/safari.html
with lots of feedback. I would like to see favicons in the address bar and the bookmarks sidebar, but I won't fuss if I don't get them The biggest problem is not having them in the Favorites bar, where a favicon alone takes up little space and is far quicker to identify than reading low contrast grey on grey text. This alone is enough to keep many users with Firefox, Chrome or Chromium, rather than using Safari. If Apple really prefers to make the Mac more awkward to use, but more consistent in minimalist appearance with iOS, I have to wonder why. Who is more important to you, Apple? The users who buy your products, or the egoists on the design teams?