I can accept that SAMP is not currently designed for pulling data from an application, but I don't understand the reasoning (nor your comment about using HTTP, maybe I'm just being dense).

As a real world example that would benefit from pulling, `astropy.io.ascii` has a built-in AASTeX table outputter with a few knobs to twiddle.  So I can imagine providing my colleague who uses Topcat with a few line function that grabs a Topcat table specified by name and outputs the AASTex table.  Without being able to pull, I have to include instructions to run this function, then focus on Topcat, bring up the table, and then do the three menu clicks in order to push the table to astropy.

Generally speaking, it just seems that being able to pull would improve interoperability.  I'm probably biased by doing almost all interactive analysis in IPython, but the first thing I wanted to do with this high level interface was to round-trip some data to Topcat and back via the console.