In terms of international lounge access, I don't think there is any difference between booking a VA flight numbered codeshare and booking the flight under the operating carrier's flight number.

Status credits can be earned for partner airline flights, you don't have to book the VA codeshare for those either. But it is subject to some terms, which has been covered. Sometimes it is better to book the VA flight, but sometimes it is worse (for example I find economy flexi-fare tickets booked directly with SQ often are cheaper than the lowest price VA codeshare.. and they earn TWICE the status credits!).

As long as the partner airline fare qualifies for SC, the only reasons to book the VA codeshare are for the additional points bonus for elite members, and for qualifying sectors.