It's not like putting lines on paper has changed much over even 100 years. Some tech has gotten better, but there's no reason why you should expect animation to improve to any significant degree with time. Any more than you should expect a painting made today to be better than a painting from hundreds of years ago. I do think the quality of the average TV anime's animation has improved over the 90s and before though. The "I was born in the wrong generation' crowd really doesn't seem to know just how shitty TV animation could get.