ULTRAMAN was made as a series for general audiences, which is why it aired in prime time. ULTRA Q was a huge media phenomenon and so was ULTRAMAN - these weren't kids' shows, they were for all ages. Again, the level of acceptable violence and sex allowed in Japanese films and television shows used to be shocking in comparison to the U.S., so remember that everything is relative.
Also, if you will notice, the level of bloodletting in ULTRAMAN is only in the first 13 episodes. I can only recall episodes 8 and 10 containing flowing blood. There is literally no blood in later episodes (except for a little on Drako's shoulder in episode 37). Tsuburaya's now-famous quote about not showing blood and gore, was coined around this time. Not before. Obviously, he directed the effects for WAR OF THE GARGANTUAS (1966), which has one of the monsters eating people (off screen, but the impression is grisly -- I saw it when I was a kid, and it was frightening -- what you DIDN'T see was positively scary).
When Tsuburaya realized that millions of children were watching his shows, he decided to make them the violence less cruel -- within the confines of a series about a superhero fighting monsters. After Tsuburaya died, and then his first son, Hajime, the gloves were off -- ULTRAMAN ACE (1972) features monsters being ripped in half, people melting, and all sorts of violent and bloody deaths. Of course, in the later shows, like ULTRAMAN 80 (1980) to ULTRAMAN MEBIUS (2006), this has been quite tempered.
If the violence in ULTRAMAN was too much for the U.S. in 1966, it would have surely been edited out. It wasn't, except for Ultraman ripping off Jiras's frill, which was considered cruel. U.S. Television Standards & Practices were much different in those days, but because of shows like ULTRAMAN and SPEED RACER, Children's Television was to change drastically in the 1970s and 1980s, in regards to violence and even hand-to-hand combat (which got ridiculous in the 1980s).
In the late 1970s, SPECTREMAN (1971) was imported to the U.S. and they cut out a lot of monster slicing and dicing, as well as most -- if not all -- human death scenes. Sometimes, episodes didn't make sense because of the censorship. If SPECTREMAN had been produced and imported in the 1960s, not much would have been cut.
U.S. Television used to be incredibly violent in the 1950s-1960s, when some of the best television shows were produced. Things are getting better in terms of non-sanitation and reality in the last decade, but I don't think we need more violence. In America, violence isn't the problem, sex is. That's where the repression really is, and which causes the violence.
Anyhow, ULTRAMAN was not considered violent at the time it was produced. Also, remember that in the original version of STAR WARS, Han shot first...
