I should probably avoid the derail, but I'd argue that the episodes we do get are an overall better production quality for the time than what Star Trek or other comparable shows had. Recurring cast size is also much larger than other regular shows. Plus, premium subscriber networks generally don't do the typical Amercian TV market cycle unless it's a news or "live" weekly show (Real Time with Bill Maher, Real Sports, to name a couple).
It's also worth noting that the "13 episode season" is comparable to scheduling in ever other media market outside the US. A lot of shows in the US don't make it past a couple of seasons because they're so long, yet last just as many episodes over 2-3x the number of years in other markets. Also worth noting that ABC, NBC, and Fox Networks (Fox, FX, FXX), at least, are picking up on this scheduling style to provide a wider range of shows during "off seasons" or splitting up certain less popular time slots.