Please see the contemporary account by the Roman philosopher Seneca on the Games in the time of Emperor Caligula:

"There is nothing so ruinous to good character as to idle away one's time at some spectacle. Vices have a way of creeping in because of the feeling of pleasure that it brings. Why do you think that I say that I personally return from shows greedier, more ambitious and more given to luxury, and I might add, with thoughts of greater cruelty and less humanity, simply because I have been among humans?

The other day, I chanced to drop in at the midday games, expecting sport and wit and some relaxation to rest men's eyes from the sight of human blood. Just the opposite was the case. Any fighting before that was as nothing; all trifles were now put aside - it was plain butchery.

The men had nothing with which to protect themselves, for their whole bodies were open to the thrust, and every thrust told. The common people prefer this to matches on level terms or request performances. Of course they do. The blade is not parried by helmet or shield, and what use is skill or defense? All these merely postpone death.

In the morning men are thrown to bears or lions, at midday to those who were previously watching them. The crowd cries for the killers to be paired with those who will kill them, and reserves the victor for yet another death. This is the only release the gladiators have. The whole business needs fire and steel to urge men on to fight. There was no escape for them. The slayer was kept fighting until he could be slain.

'Kill him! Flog him! Burn him alive!' (the spectators roared) 'Why is he such a coward? Why won't he rush on the steel? Why does he fall so meekly? Why won't he die willingly? "

Unhappy as I am, how have I deserved that I must look on such a scene as this? Do not, my Lucilius, attend the games, I pray you. Either you will be corrupted by the multitude, or, if you show disgust, be hated by them. So stay away." http://www.eyewitnesstohistory.com/gladiators.htm

So we can see that certain Romans, at least among the educated upper class, disdained the gladiatorial games as a brutal entertainment for "hoi polloi" i.e., the mob of Plebs. I think we can make some parallels to today's culture. Some questions that come to mind: Why is UFC so popular? Who watches cage fighting? Why is violence such an acceptable theme for major Hollywood movies, much more so than sexual content? What does this say about human nature? Obviously, these and other questions of a philosophical bent have no easy answers, but they are worth asking and contemplating.

this should go without saying but people in the past or in other cultures aren't automatically sadistic or psychopathic or whatever because they have different standards to us