I was going to reply that just because intel did something funny doesn't mean that it was the beginning of the story. but it turns out that the release of the 8087 predates the ratification of IEEE floats by 2 years. in addition, the primary numeric designer for the 8087 was apparently Kahan, which means that they were both part of the same design process. of course there were other formats predating both of these
The floating point "standard" was basically codifying multiple different vendor implementations of the same idea. Hence the mess that floating point is not consistent across implementations.