Am I missing something? It sounds like the advocates of this thread are asking for a way to cheat the system to multi-rapid-cast things they shouldn't be able to.
The "point of no return" in a cast is there to give higher latency players the benefit of the doubt when moving; it's not there to say "go ahead and start doing something else now". Clipping a cast to start casting sooner is far less innocent than clipping a cast to dodge.

If the damage dealers in party are not putting out enough damage with the system as it is, there are far graver problems than the inability to start casting the next action early.