[Will Snow] “How on earth was it allowed to get like that…”
A combination of technical limitations and lazy engineering. Whoever was the bright spark who decided to shift the NTSC frame rate from 60hz to 59.94 should be immortalised as creating the most grief in both the 20th & 21st centuries.
By pure luck I was born in a PAL country so we have far fewer technical conundrums and a history of superior engineering.
The most important thing to consider is how your animation is going to be delivered. If it is for broadcast TV then most people will be viewing it as standard def interlaced.