I think the general problem with intra-alliance landtrading is that they've got simpler access to break information, saving themselves many turns, as well as coordination, since they're all in one place.
Other political reasons include the fact that you could essentially pact out, and landtrade in your own bubble... which is something I know many alliances will not accept. Some people may say "hey, if you cant beat em, join em." The problem with that is that if everyone adopted this idea, we'd inevitably end up with most, if not all, tags either trading within their own ranks, providing no interaction between alliances(and removing one of the most valid reasons for war), and probably generate a bunch more untagged suiciders.
This game doesn't need less interaction between tags- if anything we need more. That being said, though, I feel as though you keep the douchebaggery to a minimum with your "grabbing agreements" or what-have-you, it is perfectly acceptable, and has the capacity to generate significant amounts of goodwill between tags.
That is, as long as there's a clearly defined, server-accepted definition as to what "abusive land trading" is. Anyone else remember the outcome of one of the last landtrading threads? Nothing. We need to work on that. For me, it would be having more than one exchange of hits within a 24 hour period- anything more than that and you'd have to handle standard ROR escalation.
