Why does the new space craft look like a capsule?  The simple fact is that between a capsule and a space plane like the shuttle, a capsule is the better vehicle for a direct return trip from interplanetary space to Earths surface. 
People my age, early-mid 30's, and younger look at a space capsule as being an artifact from a past era.  The 1960's and 1970's were the age of the capsule.  Then in the 1980's and 1990's we had the Space Shuttle Program in full swing.  The shuttle was so much more than a spacecraft.  As president Reagan put it the Shuttle was a symbol of our aspirations for freedom. 

In the below it can be said that he dedicated a Shuttle launch to people who 20 years latter would become the Taliban. 


There were many solid reasons for abandoning a type of space craft which for a time was as much a national symbol as the Bald Eagle or the Statue of Liberty. 

Assuming a new space-plane could have been built and made safer than the old shuttles why not use it to return directly from Mars?  Why not take a proven space vehicle, like the X-37B, and make it into a manned version?  




Space-planes like the X37B and the shuttle would have only been workable as a sort of space taxi which would take personnel and supplies up to a space station.  The space-station would be where a Mars craft would depart from and return to in this scenario.  However, maintaining the orbital infrastructure it would take to construct and stage a craft in orbit is cost prohibitive.  There would need to be a viable long term program for a space plane and a space station.   NASA has learned the hard way that banking on Congress providing  a large amount of funding in the long term is not wise. 
While developing a Mars program the choice was made to design a space craft and infrastructure which would not depend on the existence of a Space-Shuttle style space plane, and a space station.   The Orion and it's infrastructure will not rely on any other part of our space program or that of any other nation.  Even if all the rest of our space infrastructure is abandoned at some point, the Mars program can still be saved. 
There are aerodynamic reasons as well. 

A space-craft with wings like the space shuttle and the X-37B would not be the best aerodynamic shape for a craft returning to Earth at the velocities of a Mars return.  The amount of energy that would need to be dissipated as the craft reenters from the Mars-Earth trip is much greater than the low Earth orbit reentry the Space Shuttle was designed for.  The leading edges of the wings of space-planes experience greater heating than any other part of the craft.   

A bell shaped capsule would spread the heat of re-entry out over a larger area.  This is inherently safer and more aerodynamically stable than a space-plane. 

TL;DR If like me you miss having a beautiful aerodynamic sleek bird like space craft get over it.  A capsule is and was the correct choice for interplanetary missions given the proven and tested technologies and materials available. Don't count out the basic design of a space-plane though.  For other purposes it is superior. 
Update:
There is talk of a manned version of the X37 (here , here) but don't hold your breath.  The C37 program has been in development since the late 1990's.  It could take 5 to 10 years or more for the crewed X37-C to make a debut.