Half the features of Excel cannot deal with named cells. Try for example to use named cells in Conditional Formatting. Doesn't work at all, ranges cannot be named cells or tables, and condition formulas can only reference named cells with extremely ugly contortions.
There are lots and lots of additional examples of similar problems.
Excel is a loose agglomeration of unrelated features hidden under a pretty GUI.
Worked with the Excel team on the 2007 beta. They want to do this too, but program managers give them a hard "No." If you touch even one thing there is a cascade of side effects that will drag you off the local maximum.
The PMs are right. It would be expensive to do this and it would piss off existing customers.
It does, but that too is a half assed feature so users struggle with it IRL