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Agreed with the above, implementing a delete row link is trivially easy using an additional column and a rich text display field.
Filtering and sorting are a trickier issue - the problem is, the inherent capability of the editable grid is based on having an array of data on-form stored in a consistent order. If sorting were implemented it would be super tricky to determine how to keep track of which data in which row(s) has moved where at any given instant. Filtering would be even more complex based on the fact that you might have new or edited, but unsaved, data stored in a row that your filters now prevent you from seeing. These are reasons why sorting and filtering aren't even very often implemented manually on editable grids by even experienced developers - it turns into a complicated mess.
I suppose similar might be why we can't have paging by default.
Just imagine 1000 cells, that is 10 pages of 10 rows each or 100 entries with 10 columns, not unreasonable. Now, one of them has a validation pop up and needs to be fixed, but which one? We don't want to do that to users.
If there were a way to make paging super smart, like auto page to the one with an error, it could be awesome and possibly a differentiator between Appian and other platforms. Solve the inherent nightmare of sorting and filtering, and it could be a game changer.
My fear for this approach is that such an implementation would very likely have to sacrifice either flexibility, or design simplicity, or even both of those.
And we would be flooded with Appian based Excel implementations ...