[BioC] counts vs exprs

[Ed Siefker]

I was trying out the DESeq package, whose documentation says:

"The CountDataSet class is derived from Biobase’s eSet class and so
shares all features of
this standard Bioconductor class."

So I tried exprs() on it, which didn't work.  Of course, CountDataSets
have their own
counts() function.  I was just wondering why they have different
names.   Why not make
count data accessible through exprs()?  Is the reasoning behind this
due to R internals,
or is it biologically motivated?