I think your rant is somewhat misplaced as inferring the user desire in this case is not always possible. In general, I find it to be dangerous behavior when merely adding data changes formulas. I think the proper action is to insert a row.
On the other hand, having defined tables with in a workbook is great idea, but it makes the whole application a wee bit more complicated. I'd like to see it in something of a hybrid between Access and Excel, where you can mix structured and tabular data.
No, I don't want the spreadsheet to "infer" my desire or for it to change my formulas when I enter data.
The formula should describe the calculation I want performed and it should continue to work even when I enter new data. For example, if I have a "defined table" as you say, I should be able to ask it for a sum of a column in the table, and have it continue to work even if I add new data to the table, with hacks or trickery or invoking obscure commands.
On the other hand, having defined tables with in a workbook is great idea, but it makes the whole application a wee bit more complicated. I'd like to see it in something of a hybrid between Access and Excel, where you can mix structured and tabular data.