absolutely.
Vince - this would be a solid feature enhancement ENH. Most of us here are aware there are caveats (like it counting data that will be culled upon next compress) and understand it might overestimate. however, a ballpark idea of size of FC would be very, very, very helpful. First, for publishing and estimating credits as Adrian mentions above. Second, to periodically check in on layers to see if they have runaway data or size expansion. Perhaps even write a trigger or routine to alert if something hits a certain threshold. It would be nice to abstract this away from the RDBMS so we can have one way to check this; no need to look up a particular RDBMS command. Frankly, even if just the basic three are supported, would be fine. I'm sure most of us here are on SQL Server, the rest, probably a mix of Oracle, SAP or Post.
And also, some of us (me at the moment) do not have access to SQL Server. I've used SSMS and other RDBMSs with T-SQL. But many places simply have security and data siloes. In my case I don't have admin to anything and no access to SQL Server. Thus, a way to see FC sizes in Pro would be great.