Why don't more size make use of the CSS tab-size attribute? On this site for instance I can open the Chrome console (F12) and under Styles on the right I can write tab-size: 4 and it instantly fixes the incorrect 8-size tab indentation by changing it to 4-size indentation. Try it here:
I've tried finding a Chrome Extension for it, but the word "tab" is overwhelmingly used to refer to browser tabs and not the tab character. If one doesn't exist I think I'll try and see if I can make one - it should be simple to change the master CSS rule for all webpages to include "tab-size: 4" or whichever size you set in the settings.
Everything moves on and you can't expect them to offer support for a OS that is 3 releases old.
Technology changes with time and the software adapts to them changes. Now we are heading into the mobile age of tablets, smartphones, ect. And I believe Microsoft is making the right decisions with their new OS's.