alt Hacker NewsThat's the thing, bigger datatypes means less effective memory throughput. From that perspective 16-bit or even 8-bit floats are often more useful than 80 or 128 bit floats. Same problem with 64 bit pointers and why it's often better to store narrower indices instead of full pointers, data can be packed more tightly and accessed more efficiently.
The point about large word lengths is you get higher data throughput, and faster processing, because everything is going through fat pipes into a big parallel machine with multiple levels of cache and vectorisation.
The issue is the utility of floats at different precisions. 128-bit floats have some benefits for high-end scientific applications, but the extra cost and complexity over 64-bit hardware would only make sense for specialised scientific supercomputing. So far it just hasn't been worth it.