IMO relative orders are not worth the development time they'd take to implement.
Someone just needs to port one of the market maker bots to windows/mac and then anyone would be able to do the achieve the same thing with little effort.
Yes, based on the links above, that appears to have been the view taken by the developers till v1.0 is out, and it was inarguably necessary to prioritise things. I'm more reluctant to accept that bots can accomplish the same thing as relative orders however.
I still remain interested in the question I raised above - if there were a market with only relative orders, is this a lot more feasible because the matching is essentially just like a market with only limit orders, and it avoids dealing with the interaction between the two? This may seem like an odd and purely hypothetical question, but it has practical importance to some design possibilities I've been thinking about.