Because you need a pretty decent connection to do that too
An SSH terminal connection (i.e. text-based connection to the server) would work but I wouldn't trust marina connections to be reliable enough for a reasonable VNC style interface (be it Citrix or otherwise)... but now I'm falling into geek-speak in the sailing forums!
Development remotely is not really a big deal, but a non-insignificant part of contract development is client relations. Hard to do that (with integrity) from a boat in the middle of the ocean and an unpredictable connection to the Internet. Retail development might work, but I am not sure how well contract development might go.