In fairness, Most of the newer model external BBs from Shimano that you can buy now will use the smaller diameter interface. You need tool TL-FC25 to use the older tool.
You can still buy some BBs that use the larger size, I think the lower end (Tiagra, Deore) still do.
The new tool would probably get just as much use as any other BB tool.
Only reason I don't have one yet is that I haven't had to fit a newer BB yet!