Actually, it's not just star alliance gold cards, it's SQ star gold card holders that they don't allow in the F & J lounges, so not sure how that's anti-star alliance, just anti-economy passengers! They do allow anyone holding a star alliance J boarding pass for travel that day (eg on TG, UA, LH, LX, OZ, etc) into their J lounge.
Now SQ do come under criticism for refusing star alliance gold members access, at certain times, to their SilverKris Lounge in SFO. Ironically the main reason for that is that you can move airside between the international terminal and UA terminal (which hosts domestic flights), and the main reason people want to use the SQ lounge (apart from UA elites not having access to their own lounges on domestic itineraries) is because the SQ lounge has a shower and arguably better catering than the UA lounge (I say arguably, because I've never been to the UA lounge there and the SQ lounge catering is not great). So SQ not providing a shower and the best possible catering - for economy class star alliance gold passengers at its hub is "thumbing it's nose at star alliance", but UA not providing showers and arguably low level catering at one of its main hubs, is is not "thumbing its nose at star alliance"?
Bottom line, star alliances weakness is lounges and the fact there is no mutual recognition of the uber elite tiers (LH Honors Circle, SQ PPS, UA Premier 1K etc). If you're after fantastic lounge experience each and every time, and alliance wide recognition of top elite tier, better stick with oneworld. If you can accept the weakness, star alliance is fine.
VA thing wedges in between it all, one positive VA elites, at least get access to the SQ KF Gold lounge travelling MI (not a privilege extended to * golds). It would diminish a lot of the complaints though if however VA WP's (but not SG's) got access to the better lounges at Changi.