Hi Asobo,
in its current state the ATC approach procedures are not really usable for IFR in my opinion.
For approaches ATC assigns transitions to final approach by default instead of vectors, but at many airports that have a variety of different approach procedures it most of the times assigns ones that cause major detours or assigns them in an unrealistic manner. If instead you ask ATC for vectors, I have yet to see ATC giving me actual vectors, although it confirmed your request. Currently it is really hard to complete an at least reasonably realistic flight with an airliner when counting on the in-built ATC.
With FSX ATC and it giving vectors as default, at least you get to complete every flight in a realistic manner. Even more so, that at most real airports, the published procedures just are used as an initial routing for the incoming flights (already filed in the flight plan before the flight), after which ATC takes over with vectoring to optimize traffic flow.
Why can’t you just give us FSX approach logic back? In my opinion it is the best compromise to have as realistic procedures as possible within a flightsim.