I think most of the recent posts have been right on point. Last I checked, this is a discussion board, not a question board, and from what I see, everyone is giving their own interpretation as to "why Apple has gotten rid of the option to open a new window on double click". Looking at the trend of how things have gone over the past few years is how I think you answer that question. Personally, I used to be a power user and relied solely on mac. Unfortuantely, I have shifted the focus of my work and the tools I use simply because Apple doesn't care to provide them anymore. Is it because they want to cater to a more generic user to make more money? Probably, and as they should if their main goal is to run a business in the effort to increase the cost of their stock. Are they shunning their original base by doing so? Absolutely. When you look at this whole chain of events from the rarifed atmosphere, you could have seen this coming a lot earlier...
- Xserve RAID is discontinued (understandable, they didn't want to play in the enterprise storage market)
- Xserve is discontinued (this was a rather nasty one, and they showed they weren't interested in enterprise)
- Xsan is *********** (multi-OS version cluster support was canibalized)
- OS X Server was turned into a toolset (death of the pro server offerings)
- Final Cut Pro was turned into an X app (features were severly cut for a long amount of time)
- Rapid updating of OS (to make it harder for professional, or even prosumer apps, to catch up for compatability)
and now you're finally seeing it bleed from the pro, to the prosumer to even the veteran consumer base. It's simply just a lot more apparent now but it's been a long time coming. Most consumers will just accept it as it comes and adapt, but there will be those from the original base that will not. I still use a Mac Mini for doing work, but the 3 Mac Pros, 11 Xserves and 5 Xserve RAIDs have all been replaced by Dell.
Just in case there's any confusion as to whether this is a rant or proper discussion, to simplify:
Q: Why can't I double click and open a folder like I have been able to for over a decade?
A: IMO, because Apple decided that it doesn't make sense from a UX perspective anymore given the new consumer base they need to appease to make a buck. Given their behavior over the past 2-3 years, it's not surprising either and my approach has been to move to other solutions that best fit certain needs and remain using Apple for what I think makes sense.