Well, the answer appears to be in the thread for your first link:
It's unfortunately not as simple as finding someone who wants a feature to be a certain way. Merging these two options into one eliminated a class of bugs that originated from setting them differently; we didn't consider changing this simply because we felt one fewer text box would constitute a significant improvement. In the absence of a critical mass of users who voiced negative feedback, we made the decision to update the options.
And those 8 comments weren't the only feedback they got, apparently. Quoting yet again:
Regarding user feedback on the decision to merge these two options, we asked a wide variety of people and phased in the changes gradually. We blogged publicly about the potential change on the VS Editor blog (admittedly not the most widely-read VS blog, but readership was significant enough to generate discussion): http://blogs.msdn.com/vseditor/archive/2009/03/19/how-do-you-use-tab-size-and-indent-size.aspx. We solicited feedback from members of Microsoft's MVP program, who spend a lot of time in Visual Studio, and from many internal teams and developers who use Visual Studio. We also phased in the change gradually: for Beta 1, Indent Size was disabled/grayed out and always set to the same value as tab size. In the absence of negative customer feedback on this, we merged the Tab Size and Indent Size options into a single “Tab and indent size” option for Beta 2.
I'm not saying it's a good idea, just that Microsoft appears not to have just inflicted this on their users without at least some consultation. I'm no Microsoft fan-boy in case you think I'm an apologist, other than XP at work, I pretty much use al free software. It just seems to me they may not be totally in the wrong here. And I have had experiences with customers trying to get changes made to software late in the cycle - it's a royal PITA :-)
More worrying to me would be the comment from your second link:
Visual Studio 2010 can support multiple font faces and multiple font heights
Colour and italicise my code all you want, but you'll have to prise my beloved fixed width font from my cold dead hands!
And I've just noticed that MS went out of their way to actually give a workaround to those people who vehemently want the setting kept separate. The comment on the second link, dated Dec 16 2009, gives an editor extension that allows different values to be set for tabs and indents. This is pretty darn good service if you ask me.