I am abit disappointed that 2.1 default theme didn't improve..its basically a rehash of Curve theme, with a few more "boxed" items. It doesn't reflect the new look on the net at all IMHO. But thats just my opinion of course. At least I am working on getting out some of my new ideas, and they do have a more modern style. Though I leave it to others to be the judge of that of course. 
no offense to those that put effort into curve2, but they are not really themers IMO [including myself for some changes]. we dont really have a themer on the SMF team to put their touch on the theme. we have people that think they know how to create themes.
I am not saying everyone is "useless" though

..Antechinus was onboard afaik? ..but from my time on the team before 2010 it was increasingly clear that the notion that all team members were equal in determining what this and that should look like. Which was a bit strange, as I didn't question whether some core function should be done this way or not. It worked when I was present - the Curve them is almost pixel-perfect my intial idea - but I fear it changed after I left. So while there may be people that could, they may have not been allowed.
Be that as it may, you are probably correct about no-one truly "into themes" atm in the team. Creating the code, stacking up well known layouts etc. isn't that hard..the real hard part is coming up with that mix of innovative idea and user-friendly operation. Lord knows I been down road many times over the years lol, some worked out great, others not so much. in the default theme corner I think I managed to pull off a mix between new and familar..both NDT's were received at first with "no, this cannot work." from the users.
Its 2016 now. 2008 were the Curve year lol, and Core(the 1.1 NDT) were 2006 year. Curve2 was around 2012-2013 I think..or maybe abit later. 2016 SHOULD be the year it changed, but I fear it will not be..
Boy I could write lots here..but at least one thing I want to repeat(I have prob. written it before lol) and that is that it IMO was a mistake to further make default theme have so many dependencies. Anyone wanting to start fresh on a theme will have just as much hard time doing it with 2.1 as they have with 2.0, even more due to many decisions that really is theme related, be put into sources. I mean..how are they going to promote fresh looking themes if they take away the encouragement to do so?
A long time ago(a very long time lol) the famous [Unknown] acknowleded that themes were really a corner of its own, that Sources should stop dictating what themes could do. That stuck with me, and I think prob. was one of the reasons I could do Curve so drastically different from core. Which I am pretty sure he didn't quite like lol. Themes are not evil, trusting them to best make use of the data given, is the best way to be sure they thrive and be many(..)

..not be given strict directions on how to look. (examples, gif files in sources, ready-cooked strings for links etc., css that only appear FROM default for different browsers, javascript libraries that cannot be changed without hacking Sources..and so on)
Sorry for the lenghty reply.