Matlab FFT not producing symmetric spectrum
The problem comes from the DFT size. Try the code below that uses power of 2 fft.

T = 1e-4;   
fs = 1/T;
pulse = rcosdesign(.5, 6, fs);
L = length(pulse);
Nfft = 2^nextpow2(L);
ft = fft(pulse,Nfft);
ft = fftshift(ft);
ft_mag = abs(ft);
freq=(-Nfft/2:Nfft/2-1)/Nfft*fs;
plot(freq,ft_mag)
axis([-3 3 0 max(ft_mag)])