You listed what the difference of Dx and DxHR was and I believe this example shows best what's wrong with games these days.
Deus Ex gave you a various assortment of tools and didn't limit how you could use them.
DxHR gave you a more limited selection of tools and limited how you could use them to avoid people possilby breaking the game or finding an amazing solution (there's always a risk of going both ways with freedom) I believe it's called streamlining.
It's like Lego 20+ years ago and modern Lego where you already have a prebuilt set and can't really do much else other than building what you're meant to build. It's cool, but you have nothing else to do with it.
DxHR was a good game because it was well made and carried over enough of the features and gameplay from the original to weigh over the issues and limitations such as the one button takedowns, AI & level design limitations, easy difficulty and a lot of the augs being useless (the MGS ones) Mentality wise I can still argue that it didn't have what made the original great. Even if you had multiple paths they were all carefully preplanned for you to find.
The problem with Thief4 is not only what they've showed so far, but also the attitude of the developers. Does it reflect from any of the interviews they've done that they actually care about the Thief mentality? Sure it will most likely turn out a good game since it's an AAA production. But the problem is that it's not going to be a Thief game.. since it's an AAA production and catered for the majority. The majority weren't Thief players by todays standards, so they can't make it Thief.
If you make a new IP, go ahead I won't complain and people won't complain. I'm sure people might even say "woah, this game has a nice mix of Dishonored and Ass.Creed with a Thief vibe to it.." But if you take the Thief name and then make the changes they've showed and write things like that people will be pissed.