YOu can!
And you should.
I own 17 pairs of black yoga pants and, like you, that's all I wear these days.
That being said I've also got 5 pair of Eileen Fisher black spandex pants, which feel even better than yoga pants.
And if I have to dress up, I just wear a nice Eileen Fisher top over stretchy black pants.
I'm not plus size, but Eileen Fisher looks terrific on larger bodies and is super comfortable.
Nothing is overly fitted and everything flows.
It costs a fortune -- but you only need one or two tops and they last FOREVER.
I bought a gorgeous Eileen Fisher jacket to wear when I appeared on the Today Show in 2013 -- and I still wear it whenever i have to dress up.