I doubt anyone can accurately judge Sparta's legacy by only comparing Sparta's laws and society to modern laws and societies. It makes sense to also look at previous laws and societies and see how Sparta was different.
Sparta is rightly criticized for slavery and horrible treatment of Helots, who they whipped, tortured, robbed, and murdered in cold blood. However, slavery was the rule rather than the exception at that time and Sparta's enemies at Thermopylae, the Persians, also held slaves.
One way that Spartans were different from their contemporaries is that Spartan women had many of the same rights as men, far more than women in most other other societies did. Though not citizens, they owned property, got the same education as men, moved about as they pleased, etc.
Another way they differed from their contemporaries was that they had limited government- a republic. Two kings acted as joint commanders-in-chief and could effectively veto each other's decisions. General executive power lay with Ephors- elected by popular vote of citizens for a one year term. Major decisions were decided by plebiscite. A council of elders comprising men over 60 with lifetime appointments presented options to the citizens who decided by popular vote. Spartans had rule of law and even kings could be tried and punished, even removed from power and banished.
The Roman Republic was largely based on the Spartan Republic. Roman and Spartan republics served as models for the American republic. Limited government in the form of these types of republics makes greater liberty more probable.
As far as cheerleading for Sparta against Persia, I'm afraid we're late to the game, but if Leonidas hadn't fought so well and Greece had fallen, it's quite plausible that there could be less liberty in the world today.