Before the change, minrelaytxfee had no effect whatsoever on transactions the client created,
Before the change this wasn't even exposed as a user reachable knob.
The behavior is intentional and was discussed, and the implications of lowering it were also pointed out here. If it's wise or not is, perhaps, another story.
I expect that we'd split them in the reference client when we'd lower the default, the primary intention behind adding a knob was to smooth the deployment of new relay settings by giving people an option to move relaying nodes to new rules without replacing their software.
A problem here is that the people complaining where complaining specifically about what their client would create, so unhooking creation from that wouldn't have satisfied practically any of the complaints and would have created even more testing surface area.
We've never had a wallet/relay distinction, so your read on what the relay settings did is a little off. What we've had is a _mining_ / relay distinction, and in the past the wallet used the mining setting, which was equal or more restrictive than relay. (I mention this to improve your context, for the point of what you're arguing it's a very similar thing).
(FWIW, citing 'postel's law' is perhaps not the best argument, as wise as Postel was in many ways, it is now the widely held view e.g. in standard groups that he was mistaken on that point... and the result is a legacy of many incredibility costly to maintain protocols, where obscure implementation quirks have become normative. I see it more frequently referred to cynically than as good advice these days. It's absolutely applicable in wallet vs relay behavior though.)
