They dominated the sport for half a decade whilst no other manufacturer could suss out how to get closer to them. They have 18 months of difficulties and they throw there toys out of the pram..
The Renault was never a great engine in their WDC years, it was passable. Redbull just had an epic chassis to get them to the front and stay there. Now the past 2 years they have produced a POS engine that couldn't even run in pre-season testing in '14.
Redbull are spending 100's of millions dollars and can't even get a reliable engine. They have a right to be pissed.
Renault wanted this change in regulations and look at what they've produced.