I think Chinese actions in the SCS are part of a bigger trend. As was correctly noted, Russia and China are both pushing on the west in a confrontational manner. What needs to be understood is the context. The US, and many other western nations, did quite a few worse things in their time to acquire strategically important territory, then simply militarizing some reefs (annexation of Hawaii for example or simply taking over territories from Spain). And major western countries enjoy the benefits of those gains to this day. When China came to the playing table, out of non-recognition, it was relatively weak, and really had little choice but to accept the existing, rather crooked, set of rules. It should come as little surprise that now that they are strong, they want these rules changed. Much the same applies to Russia, who was dealt with in a rather regrettable manner following the end of the Cold War (promises of NATO non-expansion for example). Unless the west is prepared for a serious dialogue, involving serious changes to the international order, these conflicts will continue, and are likely to culminate in the next big war, the winners or survivors of which will be writing a new international arrangement.
This situation isn't new, and if the history of European civilization is looked at over centuries, it's punctuated by large conflicts, following which "lasting" arrangements are made at the international level, and eventually those arrangements become dated, and when they're not changed (and they typically aren't) it leads to the next big war. The same pattern is occurring globally. The current, post-WWII with some post-Cold War amendments, arrangement no longer works. It doesn't help that the US and NATO act in routine disregard of the Security Coucil. It doesn't help that Russia and China are both willing to push around smaller countries in a very neo-imperial manner, citing western behavior as precedent, or making wild claims about maritime territory (be it Russian Arctic claims or the Chinese SCS claims). But ultimately they're symptoms of the same problem. And the root problem needs to be dealt with, not the individual conflicts.