@james - it really depends what you want to build... It's best to pick the right tool for the job... Not every tool is a hammer, and not every problem is a nail.
@inautilo This is thought povoking - thanks... and... You don't even need a moral crusade. There is a ton of fairly obvious ways to recognize a higher value for light and fast web based software:
A faster experience is better UX = happier customers
Less egress = less bandwidth costs
Less output = less compute to produce it = less infrastructure cost
The list can go on and on.
@rolle - when you get into issues of bogging down the browser ... One of more interesting ways of dealing with it is to build a queue of stuff to process and work through it using window.requestAnimationFrame().
It's good for stuff beyond just animating canvas elements - I promise.